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 A120891 #14 Jan 31 2021 22:34:57 %S A120891 0,1,1,1,1,1,1,2,1,1,2,1,1,1,1,1,2,2,1,2,1,1,2,1,1,2,1,2,2,1,1,2,2,1, %T A120891 2,1,1,2,2,1,1,1,2,2,1,2,2,2,1,2,1,1,4,1,1,2,1,2,2,2,1,2,1,1,2,1,2,2, %U A120891 1,1,2,2,2,2,1,1,2,2,1,2,2,1,4,1,1,2,1,2,2,1,1,2,2,2,2,1,1,4,1,1,2,2 %N A120891 Number of primitive Pythagorean triangles with odd leg 2n-1. %C A120891 Bisection of A024361. %C A120891 Bisection of even-numbered terms of A024361 results in alternating zero terms; removing zeros gives A068068. - _Ray Chandler_, Feb 04 2020 %H A120891 Ray Chandler, <a href="/A120891/b120891.txt">Table of n, a(n) for n = 1..10000</a> %F A120891 a(n)=2^(k-1), where k=A092523(n) for n > 1. %Y A120891 Cf. A024361, A068068, A092523, A120890. %K A120891 nonn %O A120891 1,8 %A A120891 _Lekraj Beedassy_, Jul 12 2006 %E A120891 a(1)=0 inserted by _Ray Chandler_, Feb 04 2020