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 A356448 #13 Aug 08 2022 09:15:17 %S A356448 2,4,6,8,10,12,16,18,20,22,24,26,28,30,32,34,36,38,40,44,46,48,50,52, %T A356448 54,56,58,60,62,64,66,68,72,74,76,80,82,86,88,90,92,94,96,100,102,104, %U A356448 106,108,110,116,118,120,122,128,130,132,134,136,138,140,142,144,146,148 %N A356448 Even numbers k such that k^2 is in A014567. %C A356448 Even numbers k such that k and sigma(k^2) are coprime, sigma = A000203. %H A356448 Jianing Song, <a href="/A356448/b356448.txt">Table of n, a(n) for n = 1..7127</a> (all terms <= 20000) %F A356448 a(n) = 2*A356451(n). %e A356448 12 is a term since 12 and sigma(12^2) = 403 are coprime. %o A356448 (PARI) isA356448(n) = !(n%2) && gcd(n,sigma(n^2))==1 %Y A356448 Cf. A014567, A000203, A356382, A356449, A356451, A356452 (complement in the even numbers). %K A356448 nonn,easy %O A356448 1,1 %A A356448 _Jianing Song_, Aug 07 2022