OFFSET
0,3
COMMENTS
Essentially the same as A167022. - R. J. Mathar, Nov 18 2009
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = 0^n - 2*Sum_{k=0..floor((n-2)/2)} C(n-2,2k)*A000108(k).
D-finite with recurrence: n*a(n) +(-2*n+3)*a(n-1) +3*(-n+3)*a(n-2)=0. - R. J. Mathar, Jan 23 2020
EXAMPLE
1 - 2*x^2 - 2*x^3 - 4*x^4 - 8*x^5 - 18*x^6 - 42*x^7 - 102*x^8 - 254*x^9 - ...
MATHEMATICA
CoefficientList[Series[x + Sqrt[1 - 2 x - 3 x^2], {x, 0, 50}], x] (* G. C. Greubel, Jul 08 2016 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Nov 17 2009
STATUS
approved