OFFSET
1,1
COMMENTS
Essentially (rounding effects ignored) 2*n+1 divided by the scaled constant A081821.
FORMULA
Conjectures from Colin Barker, May 08 2019: (Start)
G.f.: x*(2734 - 912*x + 2735*x^2 - 912*x^3) / ((1 - x)^2*(1 + x^2)).
a(n) = (3646 + (-i)^n + i^n + 7290*n) / 4 where i = sqrt(-1).
a(n) = 2*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4) for n>4.
(End)
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Paul Curtz, Oct 15 2008
EXTENSIONS
Edited by N. J. A. Sloane, Oct 15 2008 and R. J. Mathar, Oct 17 2008
Deleted keyword more: we do not want more terms of this ill-defined sequence. - R. J. Mathar, May 12 2019
STATUS
approved