OFFSET
0,2
COMMENTS
3^(2*n+1) + 2^(n+2) = 3*(3^2)^n + 4*2^n == 3*2^n + 4*2^n = 7*2^n == 0 (mod 7).
LINKS
FORMULA
G.f.: ( 1-6*x ) / ( (9*x-1)*(2*x-1) ). - R. J. Mathar, Feb 18 2016
EXAMPLE
a(2) = (3^5 + 2^4)/7 = 259/7 = 37.
MAPLE
a:= n-> (3^(2*n+1) + 2^(n+2))/7:
seq (a(n), n=0..30);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Lagneau, Apr 26 2010
STATUS
approved