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 A007120 M0915 #27 Sep 13 2021 09:05:28 %S A007120 1,1,-2,-3,16,-10,-114,462,-496,-2952,16920,-31680,-130008,1707576, %T A007120 -14259504,138375720,-1652311680,22238105280,-321916019904, %U A007120 4959460972224,-81123831838080,1405677742882560,-25732182778727040,496324987642915200,-10061966722201900416 %N A007120 Expansion of e.g.f. (1+x)^(1-x). %D A007120 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A007120 Seiichi Manyama, <a href="/A007120/b007120.txt">Table of n, a(n) for n = 0..453</a> %o A007120 (PARI) a(n) = n!*polcoef((1+x+x*O(x^n))^(1-x), n); \\ _Seiichi Manyama_, Sep 13 2021 %Y A007120 Cf. A005727. %K A007120 sign %O A007120 0,3 %A A007120 _Simon Plouffe_ %E A007120 Signs from _Christian G. Bower_, Nov 15 1998 %E A007120 Signs corrected by _Sean A. Irvine_, Oct 17 2017