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 A067465 #16 Jun 06 2022 05:48:14 %S A067465 0,13,64,67,189,344,900,2499,3028,4253,5257,6277,9075,11516,12544, %T A067465 18739,18925,47018,49011,62355,72981,112061,125011,125653,152765, %U A067465 167820,168317,174724,179040,225492,240597,251568,261163,302128,302812,345283 %N A067465 Numbers k such that sigma(k^2+1) is a perfect square. %H A067465 Amiram Eldar, <a href="/A067465/b067465.txt">Table of n, a(n) for n = 1..300</a> %t A067465 Select[Range[0,400000],IntegerQ[Sqrt[DivisorSigma[1,#^2+1]]]&] (* _Harvey P. Dale_, May 14 2018 *) %o A067465 (PARI) for(n=0,500000,if(issquare(sigma(n^2+1)),print1(n,","))) %Y A067465 Cf. A000203, A000290, A002522, A006532, A193433. %K A067465 nonn %O A067465 1,2 %A A067465 _Benoit Cloitre_, Feb 23 2002 %E A067465 More terms from _Rick L. Shepherd_, Apr 16 2002