OFFSET
0,2
COMMENTS
As usual, "mod 3" means to choose the unique representative in { 0,1,2 } of the equivalence class modulo 3Z.
FORMULA
PROG
(PARI) A137992(n) = lift( sum( k=0, n, binomial( 2*k, k )/(k+1), Mod(0, 3) ))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
M. F. Hasler, Mar 16 2008
STATUS
approved