A307393 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. ((1-x)^(k-4))/((1-x)^k-x^k).

1, 1, 5, 1, 4, 16, 1, 4, 11, 42, 1, 4, 10, 26, 99, 1, 4, 10, 21, 57, 219, 1, 4, 10, 20, 42, 120, 466, 1, 4, 10, 20, 36, 84, 247, 968, 1, 4, 10, 20, 35, 64, 169, 502, 1981, 1, 4, 10, 20, 35, 57, 120, 340, 1013, 4017, 1, 4, 10, 20, 35, 56, 93, 240, 682, 2036, 8100

Offset: 0

Author

Seiichi Manyama, Apr 07 2019

Keywords

• nonn
• tabl

Examples

			Square array begins:
     1,   1,   1,   1,   1,   1,   1,   1, ...
     5,   4,   4,   4,   4,   4,   4,   4, ...
    16,  11,  10,  10,  10,  10,  10,  10, ...
    42,  26,  21,  20,  20,  20,  20,  20, ...
    99,  57,  42,  36,  35,  35,  35,  35, ...
   219, 120,  84,  64,  57,  56,  56,  56, ...
   466, 247, 169, 120,  93,  85,  84,  84, ...
   968, 502, 340, 240, 165, 130, 121, 120, ...
		

Links

• Seiichi Manyama, Antidiagonals n = 0..139, flattened

Crossrefs

Columns 1-5 give A002662(n+3), A125128(n+1), A111927(n+3), A000749(n+3), A139748(n+3).

Cf. A306915, A306846, A307078, A307394.

Programs

Mathematica

T[n_, k_] := Sum[Binomial[n+3, k*j + 3], {j, 0, Floor[n/k]}]; Table[T[n - k, k], {n, 0, 11}, {k, n, 1, -1}] // Flatten (* Amiram Eldar, May 20 2021 *)

Formula

A(n,k) = Sum_{j=0..floor(n/k)} binomial(n+3,k*j+3).

A(n,2*k) = Sum_{i=0..n} Sum_{j=0..n-i} binomial(i+1,k*j+1) * binomial(n-i+1,k*j+1).