A146126 Number of n X n arrays of squares of integers with every (n-2) X (n-2) subblock summing to 5 and every element equal to at least one neighbor.

0, 235, 9716, 43201, 125064, 290427, 583948, 1060251, 1783944, 2829619, 4281852, 6235203, 8794216, 12073419, 16197324, 21300427, 27527208, 35032131, 43979644, 54544179, 66910152

Offset

4,2

Links

Table of n, a(n) for n=4..24.

Formula

Empirical (for n>=8): a(n) = 416*n^4 - 6704*n^3 + 42495*n^2 - 127724*n + 155688. - Vaclav Kotesovec, Nov 30 2012

Conjectures from Colin Barker, Mar 23 2018: (Start)

G.f.: x^5*(235 + 8541*x - 3029*x^2 + 3869*x^3 + 1132*x^4 - 1212*x^5 + 430*x^6 + 18*x^7) / (1 - x)^5.

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

(End)

Crossrefs

Sequence in context: A257310 A268890 A254676 * A264325 A244007 A218054

Adjacent sequences: A146123 A146124 A146125 * A146127 A146128 A146129

Keyword

nonn

Author

R. H. Hardin, Apr 14 2009

Status

approved