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 A264103 #16 Sep 08 2021 08:56:10 %S A264103 1,1,1,6,1289,13652068,11865331748843,1232033659827201777222, %T A264103 20955050449849509663209289613921, %U A264103 76615072242390448445916336191834325715261848,76456972050113830615729276134092575545874371011199394401950,25770844284993968943713846068617488831241440984966512955013952234546614462044 %N A264103 Number of n X n nonconsecutive tableaux. %C A264103 A standard Young tableau (SYT) where entries i and i+1 never appear in the same row is called a nonconsecutive tableau. %H A264103 T. Y. Chow, H. Eriksson and C. K. Fan, <a href="http://www.combinatorics.org/Volume_11/Abstracts/v11i2a3.html">Chess tableaux</a>, Elect. J. Combin., 11 (2) (2005), #A3. %H A264103 S. Dulucq and O. Guibert, <a href="https://doi.org/10.1016/S0012-365X(96)83009-3">Stack words, standard tableaux and Baxter permutations</a>, Disc. Math. 157 (1996), 91-106. %H A264103 Wikipedia, <a href="https://en.wikipedia.org/wiki/Young_tableau">Young tableau</a> %F A264103 a(n) = A214021(n,n). %e A264103 a(3) = 6: %e A264103 [1 4 7] [1 3 7] [1 4 6] [1 3 6] [1 3 6] [1 3 5] %e A264103 [2 5 8] [2 5 8] [2 5 8] [2 5 8] [2 4 8] [2 6 8] %e A264103 [3 6 9] [4 6 9] [3 7 9] [4 7 9] [5 7 9] [4 7 9]. %t A264103 b[l_, t_] := b[l, t] = Module[{n = Length[l], s = Total[l]}, If[s == 0, 1, Sum[If[t != i && l[[i]] > If[i == n, 0, l[[i+1]]], b[ReplacePart[l, i -> l[[i]]-1], i], 0], {i, 1, n}]]]; %t A264103 a[n_] := a[n] = If[n<1, 1, b[Array[n&, n], 0]]; %t A264103 Table[Print[n, " ", a[n]]; a[n], {n, 0, 11}] (* _Jean-François Alcover_, Sep 08 2021, after _Alois P. Heinz_ in A214021 *) %Y A264103 Main diagonal of A214021. %K A264103 nonn %O A264103 0,4 %A A264103 _Alois P. Heinz_, Nov 03 2015