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A159227 1/4 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 27 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 28 10:05 EST 2021. Contains 349401 sequences. (Running on oeis4.)