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 A087969 #20 Jul 15 2024 10:23:11
%S A087969 9,45,50,63,81,99,117,150,153,171,207,225,261,279,315,333,350,369,387,
%T A087969 405,423,441,450,477,495,531,549,550,567,585,603,605,639,650,657,693,
%U A087969 711,729,747,765,801,819,850,855,873,891,909,927,950,963,981,1014,1017
%N A087969 Integers m such that gcd(2^m+1, m^2) is not a square.
%H A087969 Amiram Eldar, <a href="/A087969/b087969.txt">Table of n, a(n) for n = 1..10000</a>
%e A087969 For m = 9: gcd(513, 81) = 27 is not a square number, so 9 is a term.
%t A087969 Do[s=Sqrt[GCD[n^2, 2^n+1]]; If[ !IntegerQ[s], Print[n]], {n, 1, 1000}]
%o A087969 (PARI) isok(m) = !issquare(gcd(2^m+1, m^2)); \\ _Michel Marcus_, Aug 27 2019
%o A087969 (Magma) [m:m in [1..1020]|not IsSquare(Gcd(1+2^m,m^2))]; // _Marius A. Burtea_, Aug 27 2019
%Y A087969 Cf. A087968, A087967.
%K A087969 nonn
%O A087969 1,1
%A A087969 _Labos Elemer_, Sep 22 2003