Primes whose first and last number is 3: Difference between revisions
Primes whose first and last number is 3 (view source)
Revision as of 03:43, 4 August 2021
, 2 years agoadd 1x1, 5x5, 7x7, 9x9
m (julia example) |
m (add 1x1, 5x5, 7x7, 9x9) |
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isxbyx(n, base=10, dig=3) = n ÷ prevpow(base, n) == dig && n % base == dig
p3x3(N, base=10, dig=3) = [p for p in primes(N) if isxbyx(p, base, dig)]▼
for d in 1:2:9
▲p3x3(N) = [p for p in primes(N) if isxbyx(p)]
foreach(p -> print(rpad(last(p), 5), first(p) % 11 == 0 ? "\n" : ""),
▲println("3x3 primes < 4000:")
end
▲println("\nTotal 3x3 primes less than 1,000,000: ", length(p3x3(1_000_000)), ".")
</lang>{{out}}
<pre>
1x1 primes < 4000:
11 101 131 151 181 191 1021 1031 1051 1061 1091
1151 1171 1181 1201 1231 1291 1301 1321 1361 1381 1451
1471 1481 1511 1531 1571 1601 1621 1721 1741 1801 1811
1831 1861 1871 1901 1931 1951
Total 1x1 primes less than 1,000,000: 2387.
3x3 primes < 4000:
3 313 353 373 383 3023 3083 3163 3203 3253 3313
Line 266 ⟶ 274:
Total 3x3 primes less than 1,000,000: 2251.
</pre>▼
5x5 primes < 4000:
5
Total 5x5 primes less than 1,000,000: 1.
7x7 primes < 4000:
7 727 757 787 797
Total 7x7 primes less than 1,000,000: 2104.
9x9 primes < 4000:
919 929
Total 9x9 primes less than 1,000,000: 2053.
▲</pre>
=={{header|Nim}}==
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