OFFSET
1,3
FORMULA
For n>=3, a(n)=2+2*Sum_{k=2..[n/2]} (C(n-k,k) + C(n-k-1,k-1))*A061714(k)
PROG
(PARI) { a(n) = if(n<3, 1, 2 + 2*sum(k=2, n\2, (binomial(n-k, k)+binomial(n-k-1, k-1)) * ((-1)^k+sum(i=0, k-1, (-1)^(k-1-i)*binomial(k, i+1)*i!*2^i)) ) ) }
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Alekseyev, Jul 03 2006
STATUS
approved