login
A188444
Expansion of (1+x)*(1+x+x^2)*(1-x+x^2-4*x+x^4-x^5+x^6)/(1+x^4)^3.
1
1, 1, 1, -3, -9, -9, -6, 10, 25, 25, 15, -21, -49, -49, -28, 36, 81, 81, 45, -55, -121, -121, -66, 78, 169, 169, 91, -105, -225, -225, -120, 136, 289, 289, 153, -171, -361, -361, -190, 210, 441, 441, 231, -253, -529, -529, -276, 300, 625, 625, 325
OFFSET
0,4
COMMENTS
a(n+1) is the Hankel transform of A166300(n+3) (diagonal sums of the triangle A100754).
FORMULA
G.f.: (1+x+x^2-3*x^3-6*x^4-6*x^5-3*x^6+x^7+x^8+x^9)/(1+x^4)^3.
a(n) = -3*a(n-4) - 3*a(n-8) - a(n-12). - Wesley Ivan Hurt, Mar 17 2023
CROSSREFS
Sequence in context: A268107 A306963 A084762 * A372914 A201409 A111120
KEYWORD
sign,easy
AUTHOR
Paul Barry, Mar 31 2011
STATUS
approved