OFFSET
0,5
FORMULA
2a(n)-a(n+1)=A133513(n).
O.g.f.: x^2(3x-1)/((1-2x)(1+x)(1-x+x^2)). - R. J. Mathar, Jul 22 2008
a(n+2)=4*(2^n-(-1)^n)/9+A117373(n+2)/3. [From R. J. Mathar, Jul 20 2009]
CROSSREFS
KEYWORD
sign
AUTHOR
Paul Curtz, Nov 30 2007
EXTENSIONS
Edited and extended by R. J. Mathar, Jul 22 2008
STATUS
approved