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 A226071 #16 Aug 29 2025 11:02:57 %S A226071 0,2,5,189,3074,218685 %N A226071 Numbers k such that triangular(k)+1 is a square and triangular(k)+2 is a prime. %C A226071 Subsequence of A006451 that contains the terms k such that triangular(k)+2 is prime. %C A226071 a(7) is too large to include here (see b-file). - _Max Alekseyev_, Jan 30 2014 %H A226071 Max Alekseyev, <a href="/A226071/b226071.txt">Table of n, a(n) for n = 1..12</a> %t A226071 Select[Range[0,220000],IntegerQ[Sqrt[(#(#+1))/2+1]]&&PrimeQ[(#(#+1))/2+2]&] (* _Harvey P. Dale_, Mar 01 2023 *) %o A226071 (C) // see A226069. %Y A226071 Corresponding primes: A226069. %Y A226071 Roots of corresponding squares: A226070. %Y A226071 Cf. A226071-A226074. %K A226071 nonn,changed %O A226071 1,2 %A A226071 _Alex Ratushnyak_, May 25 2013 %E A226071 Terms a(7)-a(12) from _Max Alekseyev_, Jan 30 2014