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A159226 Number of n X n arrays of squares of integers with every 2X2 subblock summing to 26 0
42, 158, 426, 1202, 2970, 8234, 20538, 58202, 148602, 430778, 1120506, 3298682, 8679930, 25783034, 68281338, 203806202, 541575162, 1620552698 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..19.

FORMULA

Empirical (for n>=2): a(n) = 7*2^(n/2-1)*((3*sqrt(2)-4)*(-1)^n-3*sqrt(2)-4) + (-2)^(n-1) + 37*2^(n-1) + 2^(3*n/2-1)*((4-3*sqrt(2))*(-1)^n+3*sqrt(2)+4)-6. - Vaclav Kotesovec, Nov 30 2012

Empirical G.f.: 12-2*x + 2*(-6 + 7*x + 104*x^2 - 40*x^3 - 482*x^4 - 32*x^5 + 512*x^6)/((-1+x)*(-1+2*x)*(1+2*x)*(-1+2*x^2)*(-1+8*x^2)). - Vaclav Kotesovec, Nov 30 2012

CROSSREFS

Sequence in context: A263300 A299889 A092228 * A160329 A010022 A217050

Adjacent sequences:  A159223 A159224 A159225 * A159227 A159228 A159229

KEYWORD

nonn

AUTHOR

R. H. Hardin Apr 06 2009

STATUS

approved

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Last modified December 2 23:30 EST 2021. Contains 349445 sequences. (Running on oeis4.)