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A159229 1/16 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 30 0
3, 11, 29, 77, 189, 509, 1277, 3581, 9213, 26621, 69629, 204797, 540669, 1605629, 4259837, 12713981, 33816573, 101187581 (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) = 2^(3*(n-3)/2) * ((2*sqrt(2)-3)*(-1)^n + 2*sqrt(2) + 3) + 2^n-3. - Vaclav Kotesovec, Nov 30 2012

Empirical G.f.: 7/4+x/4 + (7 - 20*x - 57*x^2 + 154*x^3)/(4*(-1+x)*(-1+2*x)*(-1+8*x^2)). - Vaclav Kotesovec, Nov 30 2012

CROSSREFS

Sequence in context: A072610 A110954 A000251 * A239713 A122023 A259594

Adjacent sequences:  A159226 A159227 A159228 * A159230 A159231 A159232

KEYWORD

nonn

AUTHOR

R. H. Hardin Apr 06 2009

STATUS

approved

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Last modified June 5 16:19 EDT 2020. Contains 334852 sequences. (Running on oeis4.)