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 A001889 M3345 N1346 #24 Dec 23 2021 22:44:30 %S A001889 1,4,8,38,209,1400,10849,95516,938441,10179149,120748974,1554688240, %T A001889 21588485677,321561688748,5113709884902,86469576394028, %U A001889 1549114961438599,29309613834899864,583986501706555597,12222118836543561940,268060239251978779839,6148136982942476816891 %N A001889 Hit polynomials. %D A001889 J. Riordan, The enumeration of permutations with three-ply staircase restrictions, unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963. (See A001883) %D A001889 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A001889 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A001889 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 (unpublished memorandum, Bell Telephone Laboratories, Murray Hill, NJ, Oct 1963) %Y A001889 Third column of A080061. %Y A001889 Cf. A001883-A001891. %K A001889 nonn %O A001889 2,2 %A A001889 _N. J. A. Sloane_ %E A001889 More terms from _Vladeta Jovovic_, _Vladimir Baltic_, Jan 23 2003 %E A001889 a(21)-a(23) from _Vaclav Kotesovec_, Oct 10 2017