A166212 Number of 4 X 4 X 4 triangular nonnegative integer arrays, symmetric under 120 degree rotation, with all sums of an element and its neighbors <= n.

1, 3, 6, 14, 25, 39, 66, 99, 138, 201, 274, 357, 479, 616, 768, 977, 1207, 1458, 1788, 2146, 2532, 3022, 3548, 4110, 4805, 5545, 6330, 7280, 8285, 9345, 10606, 11933, 13326, 14959, 16670, 18459, 20531, 22694, 24948, 27531, 30219, 33012, 36184, 39476

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 + x + x^2 + 3*x^3 + x^4 + x^5 + 3*x^6) / ((1 - x)^5*(1 + x)*(1 - x + x^2)*(1 + x + x^2)^3).

a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - 4*a(n-4) + 2*a(n-5) - 2*a(n-9) + 4*a(n-10) - 2*a(n-11) + a(n-12) - 2*a(n-13) + a(n-14) for n>13.

(End)

Crossrefs

Sequence in context: A056596 A026341 A026271 * A291988 A285460 A236429

Adjacent sequences: A166209 A166210 A166211 * A166213 A166214 A166215

Keyword

nonn

Author

R. H. Hardin, Oct 09 2009

Status

approved