A159226 Number of n X n arrays of squares of integers with every 2X2 subblock summing to 26

42, 158, 426, 1202, 2970, 8234, 20538, 58202, 148602, 430778, 1120506, 3298682, 8679930, 25783034, 68281338, 203806202, 541575162, 1620552698

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