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 A001886 M2604 N1031 #24 Dec 23 2021 22:44:05 %S A001886 3,6,44,180,1407,10384,92896,911512,9913152,117788056,1519021046, %T A001886 21123287848,315034832581,5015656588706,84899016219708, %U A001886 1522394744470356,28828385427350245,574839634258405032,12039133083940334978,264216869431056251276,6063573884814663905952 %N A001886 Hit polynomials. %D A001886 J. Riordan, The enumeration of permutations with three-ply staircase restrictions, unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963. (See A001883) %D A001886 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A001886 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A001886 N. J. A. Sloane, <a href="/A001883/a001883_21.pdf">Annotated copy of Riordan's Three-Ply Staircase paper</a> (unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963) %Y A001886 Fourth column of A080018. %Y A001886 Cf. A001883-A001891. %K A001886 nonn %O A001886 3,1 %A A001886 _N. J. A. Sloane_ %E A001886 More terms from _Vladeta Jovovic_ and _Vladimir Baltic_, Jan 20 2003 %E A001886 a(21)-a(23) from _Vaclav Kotesovec_, Oct 10 2017