OFFSET
0,2
COMMENTS
For a guide to related sequences, see A211422.
FORMULA
Conjecture: a(n) = (5+3*(-1)^n+2*(7+3*(-1)^n)*n+14*n^2)/8. G.f.: (1+2*x+8*x^2+2*x^3+x^4)/((1-x)^3*(1+x)^2). [Colin Barker, Apr 18 2012]
MATHEMATICA
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 11 2012
STATUS
approved