Find numbers n in base 2 where n is prime and all it's digits are 1: Difference between revisions
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{{Draft task}} |
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;Task: |
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Find numbers n in base 2 where n is prime and all it's digits are 1 |
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<br>Let 1 < n < 10000 |
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=={{header|Ring}}== |
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<lang ring> |
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load "stdlib.ring" |
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num = 0 |
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limit = 6 |
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decList = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15] |
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baseList = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"] |
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see "working..." + nl |
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see "the first 5 elements of sequence are:" + nl |
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for n = 1 to 10000 |
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if isprime(n) |
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flag = 1 |
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bn = decimaltobase(n,2) |
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for m = 1 to len(bn) |
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if not(bn[m] = "1") |
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flag = 0 |
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exit |
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ok |
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next |
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if flag = 1 |
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num = num + 1 |
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if num < limit |
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see "" + num + ". " + "number = " + n + " in base 2 = " + bn + nl |
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ok |
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ok |
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ok |
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next |
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see "done..." + nl |
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func decimaltobase(nr,base) |
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binList = [] |
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binary = 0 |
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remainder = 1 |
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while(nr != 0) |
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remainder = nr % base |
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ind = find(decList,remainder) |
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rem = baseList[ind] |
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add(binList,rem) |
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nr = floor(nr/base) |
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end |
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binlist = reverse(binList) |
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binList = list2str(binList) |
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binList = substr(binList,nl,"") |
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return binList |
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</lang> |
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{{out}} |
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<pre> |
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working... |
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the first 5 elements of sequence are: |
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1. number = 3 in base 2 = 11 |
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2. number = 7 in base 2 = 111 |
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3. number = 31 in base 2 = 11111 |
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4. number = 127 in base 2 = 1111111 |
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5. number = 8191 in base 2 = 1111111111111 |
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done... |
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</pre> |
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