login
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
OFFSET
2,1
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Apr 06 2009
STATUS
approved