OFFSET
1,2
COMMENTS
FORMULA
a(2*n) = 2*n and a(2*n-1) = 4*n^2 - 6*n + 3
G.f.: x*(1+2*x+4*x^2-2*x^3+3*x^4)/(1-x^2)^3
MAPLE
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Johannes W. Meijer, May 18 2011
STATUS
approved