OFFSET
0,3
COMMENTS
Diagonal of the rational function 1 / (1 + y + z + x*y + y*z - 2*z*x - x*y*z).
Diagonal of the rational function 1 / ((1-x)*(1-y)*(1-z) + 2*x*y*z).
MATHEMATICA
a[n_] := Sum[(-2)^k * Binomial[n, k]^3, {k, 0, n}]; Array[a, 23, 0] (* Amiram Eldar, Jul 11 2020 *)
PROG
(PARI) {a(n) = sum(k=0, n, (-2)^k*binomial(n, k)^3)}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jul 10 2020
STATUS
approved