OFFSET
0,3
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,2,0,-2).
FORMULA
a(n) = sum(k=1..n, sum(j=floor((4*k-n)/3)..floor((4*k-n)/2), binomial(j,n-4*k+3*j)*(-1)^(k-j)*binomial(k,j)*2^(n-3*k+2*j))), n>0, a(0)=1. - Vladimir Kruchinin, May 25 2011
MATHEMATICA
CoefficientList[Series[(1-x)^(-1)/(1-2x^2-2x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{1, 2, 0, -2}, {1, 1, 3, 5}, 40] (* Harvey P. Dale, Sep 22 2016 *)
PROG
(Maxima)
a(n):=sum(sum(binomial(j, n-4*k+3*j)*(-1)^(k-j)*binomial(k, j)*2^(n-3*k+2*j), j, floor((4*k-n)/3), floor((4*k-n)/2)), k, 1, n), /* Vladimir Kruchinin, May 25 2011 */
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved