A183946 Number of strings of numbers x(i=1..n) in 0..2 with sum i^2*x(i) equal to n^2*2

1, 1, 2, 1, 5, 7, 10, 20, 37, 77, 118, 227, 385, 697, 1191, 2072, 3489, 5846, 9862, 16373, 26897, 44125, 71991, 116290, 187653, 300903, 478422, 761553, 1200692, 1893309, 2961406, 4630296, 7188253, 11155170, 17211745, 26490317, 40633554, 62126693

Offset

1,3

Comments

Column 2 of A183953

Links

R. H. Hardin, Table of n, a(n) for n = 1..88

Example

All solutions for n=4
..0
..0
..0
..2

Mathematica

r [n_, k_, s_] := r[n, k, s] = Which[s < 0, 0, n == 0, If[s == 0, 1, 0], True, Sum[r[n - 1, k, s - c*n^2], {c, 0, k}]];
T[n_, k_] := r[n, k, k*n^2];
a[n_] := T[n, 2];
Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Jul 22 2022, after R. J. Mathar in A183953 *)

Crossrefs

Sequence in context: A105459 A227048 A139133 * A293719 A291377 A005297

Adjacent sequences: A183943 A183944 A183945 * A183947 A183948 A183949

Keyword

nonn

Author

R. H. Hardin, Jan 08 2011

Status

approved