Consecutive primes with ascending or descending differences: Difference between revisions
Consecutive primes with ascending or descending differences (view source)
Revision as of 22:31, 8 April 2023
, 1 year agoDialects of BASIC moved to the BASIC section.
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(Dialects of BASIC moved to the BASIC section.) |
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Line 158:
322171 (22) 322193 (20) 322213 (16) 322229 (8) 322237 (6) 322243 (4) 322247 (2) 322249
</pre>
=={{header|BASIC}}==
==={{header|FreeBASIC}}===
Use any of the primality testing code on this site as an include; I won't reproduce it here.
<syntaxhighlight lang="freebasic">#define UPPER 1000000
#include"isprime.bas"
dim as uinteger champ = 0, record = 0, streak, i, j, n
'first generate all the primes below UPPER
redim as uinteger prime(1 to 2)
prime(1) = 2 : prime(2) = 3
for i = 5 to UPPER step 2
if isprime(i) then
redim preserve prime(1 to ubound(prime) + 1)
prime(ubound(prime)) = i
end if
next i
n = ubound(prime)
'now look for the longest streak of ascending primes
for i = 2 to n-1
j = i + 1
streak = 1
while j<=n andalso prime(j)-prime(j-1) > prime(j-1)-prime(j-2)
streak += 1
j+=1
wend
if streak > record then
champ = i-1
record = streak
end if
next i
print "The longest sequence of ascending primes (with their difference from the last one) is:"
for i = champ+1 to champ+record
print prime(i-1);" (";prime(i)-prime(i-1);") ";
next i
print prime(i-1) : print
'now for the descending ones
record = 0 : champ = 0
for i = 2 to n-1
j = i + 1
streak = 1
while j<=n andalso prime(j)-prime(j-1) < prime(j-1)-prime(j-2) 'identical to above, but for the inequality sign
streak += 1
j+=1
wend
if streak > record then
champ = i-1
record = streak
end if
next i
print "The longest sequence of descending primes (with their difference from the last one) is:"
for i = champ+1 to champ+record
print prime(i-1);" (";prime(i)-prime(i-1);") ";
next i
print prime(i-1)</syntaxhighlight>
{{out}}
<pre>The longest sequence of ascending primes (with their difference from the last one) is:
128981 (2) 128983 (4) 128987 (6) 128993 (8) 129001 (10) 129011 (12) 129023 (14) 129037
The longest sequence of descending primes (with their difference from the last one) is:
322171 (22) 322193 (20) 322213 (16) 322229 (8) 322237 (6) 322243 (4) 322247 (2) 322249</pre>
=={{header|C}}==
Line 503 ⟶ 569:
752,207 (44) 752,251 (12) 752,263 (10) 752,273 (8) 752,281 (6) 752,287 (4) 752,291 (2) 752,293
</pre>
=={{header|Go}}==
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