OFFSET
2,1
COMMENTS
Each array either has four 1's or one 4, and all other elements 0. - Robert Israel, Jun 19 2018
LINKS
R. H. Hardin, Table of n, a(n) for n=2..100
Index entries for linear recurrences with constant coefficients, signature (9,-36,84,-126,126,-84,36,-9,1).
FORMULA
Empirical: n^2*(n^2+1)*(n^4-7*n^2+18)/24. - R. J. Mathar, Aug 11 2009
From Robert Israel, Jun 19 2018: (Start)
Empirical formula confirmed.
a(n) = binomial(n^2,4)+n^2 = A014626(n^2).
(End)
From Colin Barker, Jun 19 2018: (Start)
G.f.: x^2*(5 + 90*x + 801*x^2 + 591*x^3 + 252*x^4 - 88*x^5 + 37*x^6 - 9*x^7 + x^8) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>10.
(End)
MAPLE
seq(binomial(n^2, 4)+n^2, n=2..100);
PROG
(PARI) Vec(x^2*(5 + 90*x + 801*x^2 + 591*x^3 + 252*x^4 - 88*x^5 + 37*x^6 - 9*x^7 + x^8) / (1 - x)^9 + O(x^40)) \\ Colin Barker, Jun 19 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Apr 11 2009
STATUS
approved