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 A356452 #13 Mar 09 2023 15:34:25 %S A356452 14,42,70,78,84,98,112,114,124,126,154,156,168,182,186,198,210,222, %T A356452 228,234,238,252,258,266,294,308,310,312,322,336,342,350,366,372,378, %U A356452 390,396,402,406,418,420,434,438,444,456,462,468,474,490,504,516,518,532,546,550,558 %N A356452 Even numbers k such that k^2 is not in A014567; complement of A356448 in the even numbers. %C A356452 Even numbers k such that k and sigma(k^2) are not coprime, sigma = A000203. %H A356452 Jianing Song, <a href="/A356452/b356452.txt">Table of n, a(n) for n = 1..12241</a> (all terms <= 80000) %F A356452 a(n) = 2*A356454(n). %e A356452 14 is a term since 14 and sigma(14^2) = 399 have a common factor 7. %t A356452 Select[2 Range[300],!CoprimeQ[#,DivisorSigma[1,#^2]]&] (* _Harvey P. Dale_, Mar 09 2023 *) %o A356452 (PARI) isA356452(n) = !(n%2) && gcd(n, sigma(n^2))>1 %Y A356452 Cf. A014567, A000203, A356448, A356453, A356454. %K A356452 nonn,easy %O A356452 1,1 %A A356452 _Jianing Song_, Aug 07 2022