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 A359316 #8 Feb 16 2025 08:34:04
%S A359316 1,5,13,85,61,221,761,1013,2813,12013,23545,54781,16381,196565,425965,
%T A359316 770041,3137513,7663613,13629421,20962813,63946741,121602013,
%U A359316 192805885,499122013,989724541,2411720701,6435110905,17162301181,29929502461,63753420281
%N A359316 a(n) is the smallest centered square number with binary weight n.
%H A359316 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CenteredSquareNumber.html">Centered Square Number</a>
%H A359316 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%e A359316 221 is the smallest centered square number with binary weight 6 (221_10 = 11011101_2), so a(6) = 221.
%t A359316 seq[len_,nmax_] := Module[{s = Table[0,{len}], n = 0, c = 0, bw, cs}, While[c < len && n < nmax, bw = DigitCount[cs = 2*n*(n+1) + 1, 2, 1]; If[bw <= len && s[[bw]] == 0, c++; s[[bw]] = cs]; n++]; s]; seq[30, 10^6] (* _Amiram Eldar_, Dec 26 2022 *)
%Y A359316 Cf. A000120, A001844, A089998, A358932, A359315.
%K A359316 nonn,base
%O A359316 1,2
%A A359316 _Ilya Gutkovskiy_, Dec 25 2022