OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (0, 1, 0, 1, 0, -1).
FORMULA
G.f.: (1+2x+3x^2+3x^3+4x^4-x^5)/((1+x^2)(1-x)^2(1+x)^2). a(n)=a(n-2)+a(n-4)-a(n-6). a(2n)=A047461(n+1). a(2n+1)=A042963(n+1). [From R. J. Mathar, Oct 29 2008]
MAPLE
a:=proc(n) if n=0 then 1 elif n mod 2=0 then n+a(n-1) else 3*n-a(n-1) fi end: seq(a(n), n=0..68);
MATHEMATICA
a[0] = 1; a[n_] := a[n] = If[Mod[n, 2] == 0, a[n - 1] + n, -a[n - 1] + 3*n] aa = Table[a[n], {n, 0, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jun 18 2005
STATUS
approved