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 A126726 #12 May 21 2025 08:07:19 %S A126726 0,2,0,1,1,2,2,4,4,7,9,14,18,27,37,54,74,107,149,213,299,425,599,849, %T A126726 1199,1697,2399,3394,4798,6787,9597,13573,19195,27146,38390,54292, %U A126726 76780,108584,153560,217168,307120,434335,614241,868669,1228483,1737338,2456966 %N A126726 Number of squares (of nonnegative integers) that require n binary (base-2) digits. %C A126726 Binary equivalent to A062940, which uses decimal representation. %H A126726 Alois P. Heinz, <a href="/A126726/b126726.txt">Table of n, a(n) for n = 0..1000</a> %F A126726 Conjecture: a(n) = A190568(n)-(-1)^n for n>0. - _R. J. Mathar_, May 21 2025 %e A126726 21^2 = 441 = 110111001_2, requiring 9 digits. %p A126726 r:= proc(n) local b; b:= isqrt(n); b+`if`(b^2<n, 1, 0) end: %p A126726 a:= n-> `if`(n=0, 0, r(2^n) -r(2^(n-1)) +`if`(n=1, 1, 0)): %p A126726 seq(a(n), n=0..50); # _Alois P. Heinz_, Sep 13 2012 %Y A126726 Cf. A062940. %K A126726 base,easy,nonn %O A126726 0,2 %A A126726 Andrew G. West (westa(AT)wlu.edu), Mar 13 2007