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 A227480 #9 Sep 17 2023 10:12:59 %S A227480 3,120,528,139128,160554240,812293020528,379188080252621270252095320, %T A227480 2816640597719456759751165488439681098364673273236637971046370174350128 %N A227480 Triangular numbers of the form p^2 - 1 where p is a prime. %e A227480 139128 is both 527*528/2 and 373^2 - 1 (and 373 is prime). %t A227480 Select[Prime[Range[100000]]^2-1,OddQ[Sqrt[8#+1]]&] (* The program generates the first six terms of the sequence. *) (* _Harvey P. Dale_, Sep 17 2023 *) %Y A227480 Subsequence of A006454 and of A225115. %K A227480 nonn %O A227480 1,1 %A A227480 _Shreevatsa R_, Jul 12 2013 %E A227480 a(7)-a(8) from _Giovanni Resta_, Jul 13 2013