This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075402 #6 Dec 05 2013 19:55:38 %S A075402 1,0,1,1,2,2,1,1,2,4,1,1,6,2,7,1,4,2,1,1,2,4,1,7,6,2,1,3,4,2,3,13,2,4, %T A075402 1,7,6,2,7,1,2,4,1,1,4,6,1,5,4,2,1,3,2,2,3,1,4,10,7,1,10,20,1,1,8,2,3, %U A075402 1,2,18,1,5,6,2,1,1,8,2,3,11,2,4,5,1,4,20,5,1,2,4,15,5,2,16,1,1,6,10,1 %N A075402 Smallest number such that a(n) + T(n) is a prime, where T(n) is the n-th triangular number. %C A075402 0 occurs only once in this sequence. %H A075402 Harvey P. Dale, <a href="/A075402/b075402.txt">Table of n, a(n) for n = 1..1000</a> %t A075402 If[PrimeQ[#],#,NextPrime[#]]-#&/@Accumulate[Range[100]] (* _Harvey P. Dale_, Nov 21 2012 *) %o A075402 (PARI) for(n=1,100,a=n*(n+1)/2:print1(nextprime(a)-a",")) %Y A075402 Cf. A075403. %K A075402 nonn %O A075402 1,5 %A A075402 _Amarnath Murthy_, Sep 23 2002 %E A075402 Corrected and extended by _Ralf Stephan_, Mar 19 2003