A159227 1/4 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 27

7, 22, 45, 103, 193, 421, 777, 1681, 3097, 6697, 12345, 26713, 49273, 106681, 196857, 426361, 786937, 1704697, 3146745, 6817273, 12584953, 27266041, 50335737, 109058041, 201334777, 436219897

Offset

2,1

Links

Table of n, a(n) for n=2..27.

Formula

Conjecture: G.f.: x^2*(-7-8*x^4+32*x^3+19*x^2-15*x)/((x-1)*(2*x+1)*(2*x-1)*(2*x^2-1)) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009]

Crossrefs

Sequence in context: A320694 A261465 A033954 * A081274 A038764 A132438

Adjacent sequences: A159224 A159225 A159226 * A159228 A159229 A159230

Keyword

nonn

Author

R. H. Hardin Apr 06 2009

Status

approved