OFFSET
0,2
COMMENTS
Conjecture: the sequence is strictly increasing.
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,-1,2,-1).
FORMULA
G.f.: 1/(Sum_{k>=0} round((k+1)*r)(-x)^k), where r = 7/5.
From Colin Barker, Jul 19 2017: (Start)
G.f.: (1+x)^2*(1-x+x^2-x^3+x^4) / (1-2*x+x^2-2*x^3+x^4).
a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - a(n-4) for n>3.
(End)
MATHEMATICA
PROG
(PARI) Vec((1+x)^2*(1-x+x^2-x^3+x^4) / (1-2*x+x^2-2*x^3+x^4) + O(x^50)) \\ Colin Barker, Jul 20 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 18 2017
STATUS
approved