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 A108321 #4 Mar 31 2012 14:11:37 %S A108321 0,0,0,0,25,0,49,0,0,0,121,0,169,0,0,0,289,0,361,0,0,0,529,0,625,0, %T A108321 729,0,841,0,961,0,0,0,1225,0,1369,0,0,0,1681,0,1849 %N A108321 a(n) = n^2 if n^2 is not the difference of two primes; otherwise a(n) = 0. %C A108321 This sequence is also n^2 - A106546 %e A108321 a(4)=0 because the fourth perfect square 16 is the difference between two primes: 19-3. a(5)=25 figures here because the nearest prime greater than 25 is 29 and the difference 29-25 is 4 (an even number >2), thus not a prime; all other greater primes are odd and the difference with 25 will give an even number, thus again not a prime. %Y A108321 Cf. A106546, A106564, A098108, A106571. %K A108321 easy,nonn %O A108321 0,5 %A A108321 _Alexandre Wajnberg_, Jun 30 2005