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 A056137 #6 Dec 11 2019 23:40:24 %S A056137 0,0,0,1,0,0,0,1,0,0,0,2,0,0,1,1,0,0,0,1,1,0,0,3,0,0,0,1,0,1,0,1,0,0, %T A056137 1,2,0,0,0,2,0,1,0,1,2,0,0,3,0,0,0,1,0,0,1,2,0,0,0,4,0,0,2,1,0,0,0,1, %U A056137 0,1,0 %N A056137 Number of ways in which n can be the longer leg (middle side) of an integer-sided right triangle. %F A056137 a(n) = A046079(n) - A056138(n) = A046081(n) - A046080(n) - A056138(n). %Y A056137 Cf. A009023, A055523. %K A056137 nonn %O A056137 1,12 %A A056137 _Henry Bottomley_, Jun 15 2000