OFFSET
0,2
LINKS
FORMULA
G.f.: (1-5*x)/(1 - 20*x + 50*x^2);
a(n) = ((1 + sqrt(2))*(10 + 5*sqrt(2))^n - (1 - sqrt(2))*(10-5*sqrt(2))^n)/(2*sqrt(2)).
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Mar 26 2004
STATUS
approved