OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,3,-2,-6,-4,-1).
FORMULA
a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3) - 6*a(n-4) - 4*a(n-5) - a(n-6) for n > 5.
a(n) = Sum_{k=0..n} (-1)^k * binomial(-2,k) * binomial(2*k,n-k) = Sum_{k=0..n} (k+1) * binomial(2*k,n-k).
PROG
(PARI) my(N=40, x='x+O('x^N)); Vec(1/(1-x*(1+x)^2)^2)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Apr 08 2023
STATUS
approved