OFFSET
0,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (5,-5,-5,5,-1).
FORMULA
(1/5)[n*F(2n+2) - n*F(2n-2) + 4*F(2n+1) + (-1)^n], F(n)=A000045(n). - Ralf Stephan, May 13 2004
G.f. ( 1-3*x+2*x^2+x^3 ) / ( (1+x)*(x^2-3*x+1)^2 ). - R. J. Mathar, May 22 2013
PROG
(Haskell)
a027990 n = a027990_list !! n
a027990_list = c [1] a000045_list where
c us (v:vs) = (sum $ zipWith (*) us vs) : c (v:us) vs
-- Reinhard Zumkeller, Nov 01 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved