A166213 Number of 5 X 5 X 5 triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= n.

1, 4, 12, 30, 64, 122, 218, 364, 579, 886, 1310, 1880, 2636, 3614, 4862, 6434, 8387, 10784, 13704, 17220, 21422, 26408, 32280, 39148, 47143, 56388, 67028, 79218, 93118, 108898, 126754, 146872, 169465, 194758, 222982, 254380, 289226, 327782, 370342

Offset

0,2

Links

R. H. Hardin, Table of n, a(n) for n=0..63

Formula

Conjectures from Colin Barker, Feb 26 2018: (Start)

G.f.: (1 + 2*x + 3*x^2 + 4*x^3 + 3*x^4) / ((1 - x)^6*(1 + x)^2*(1 + x + x^2)^2).

a(n) = 2*a(n-1) + a(n-2) - 2*a(n-3) - 3*a(n-4) + 6*a(n-6) - 3*a(n-8) - 2*a(n-9) + a(n-10) + 2*a(n-11) - a(n-12) for n>11.

(End)

Crossrefs

Sequence in context: A220264 A367097 A212519 * A274250 A004036 A011797

Adjacent sequences: A166210 A166211 A166212 * A166214 A166215 A166216

Keyword

nonn

Author

R. H. Hardin, Oct 09 2009

Status

approved