A361830 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..n} binomial(2*j,j) * binomial(k*j,n-j).

1, 1, 2, 1, 2, 6, 1, 2, 8, 20, 1, 2, 10, 32, 70, 1, 2, 12, 46, 136, 252, 1, 2, 14, 62, 226, 592, 924, 1, 2, 16, 80, 342, 1136, 2624, 3432, 1, 2, 18, 100, 486, 1932, 5810, 11776, 12870, 1, 2, 20, 122, 660, 3030, 11094, 30080, 53344, 48620

Offset

0,3

Links

Table of n, a(n) for n=0..54.

Formula

G.f. of column k: 1/sqrt(1 - 4*x*(1+x)^k).

n*T(n,k) = 2 * Sum_{j=0..k} binomial(k,j)*(2*n-1-j)*T(n-1-j,k) for n > k.

Example

Square array begins:
    1,   1,    1,    1,    1,    1, ...
    2,   2,    2,    2,    2,    2, ...
    6,   8,   10,   12,   14,   16, ...
   20,  32,   46,   62,   80,  100, ...
   70, 136,  226,  342,  486,  660, ...
  252, 592, 1136, 1932, 3030, 4482, ...

Prog

(PARI) T(n, k) = sum(j=0, n, binomial(2*j, j)*binomial(k*j, n-j));

Crossrefs

Columns k=0..5 give A000984, A006139, A137635, A361812, A361813, A361814.

Main diagonal gives A361829.

Cf. A099233, A361834.

Sequence in context: A357124 A210227 A208757 * A133643 A008305 A208763

Adjacent sequences: A361827 A361828 A361829 * A361831 A361832 A361833

Keyword

nonn,tabl

Author

Seiichi Manyama, Mar 26 2023

Status

approved