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 A207322 #6 Dec 25 2023 18:13:52
%S A207322 0,-3,12,-81,558,-4095,31074,-241761,1915998,-15403839,125264226,
%T A207322 -1028198769,8505440256,-70821126339,593013903996,-4989710564097,
%U A207322 42162715062462,-357607035133503,3043168538309586,-25973801534610801,222282241838388288,-1906876619917171299,16394307639893817516,-141231930366941378721
%N A207322 a(n) = Sum{k=0..n} (-1)^k*A002893(k).
%K A207322 sign
%O A207322 0,2
%A A207322 _N. J. A. Sloane_, Feb 16 2012