OFFSET
1,1
COMMENTS
Of the 255 terms less than 10^4, 128 are positive.
LINKS
R. J. Mathar, Table of n, a(n) for n = 1..120
FORMULA
MAPLE
Maple code from R. J. Mathar, Feb 25 2008:
A000108 := proc(n) option remember ; binomial(2*n, n)/(n+1) ; end:
A107757 := proc(n) option remember ; local a; if n = 1 then 3; else for a from A107757(n-1)+1 do if add(A000108(k), k=1..a) mod 3 = 2 then RETURN(a) ; fi ; od: fi ; end:
MATHEMATICA
s0 = s2 = {}; s = 0; Do[s = Mod[s + (2 n)!/n!/(n + 1)!, 3]; Switch[ Mod[s, 3], 0, AppendTo[s0, n], 2, AppendTo[s2, n]], {n, 10^4}]; s2 - s0
CROSSREFS
KEYWORD
sign
AUTHOR
Robert G. Wilson v, Jun 14 2005
EXTENSIONS
Corrected by T. D. Noe, Jun 14 2007
STATUS
approved