A243484 Number of isoscent sequences of length n with maximal number of descents.

1, 1, 2, 1, 6, 2, 28, 10, 1, 98, 22, 2, 570, 130, 17, 1, 1842, 337, 38, 2, 13104, 2437, 318, 26, 1, 45188, 7126, 805, 58, 2, 387323, 61504, 7496, 658, 37, 1, 1422382, 196200, 20978, 1631, 82, 2, 14272601, 1971561, 220497, 19175, 1216, 50, 1, 54989728, 6713935

Offset

0,3

Links

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 0..100

Formula

a(n) = A242352(n,n+2-ceiling(2*sqrt(n+1))).

Mathematica

b[n_, i_, t_] := b[n, i, t] = If[n<1, 1, Expand[ Sum[If[j<i, x, 1]*b[n-1, j, t + If[j == i, 1, 0]], {j, 0, t+1}]]]; a[n_] := Coefficient[b[n-1, 0, 0], x, n + 2 - Ceiling[2*Sqrt[n+1]]]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Feb 09 2015, after A242352 *)

Crossrefs

Sequence in context: A321898 A284434 A306543 * A181811 A284431 A333078

Adjacent sequences: A243481 A243482 A243483 * A243485 A243486 A243487

Keyword

nonn

Author

Joerg Arndt and Alois P. Heinz, Jun 05 2014

Status

approved