OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,-1,-2,2).
FORMULA
G.f.: G(0)/(1 + x) where G(k) = 1 + 8*x + 2*k*x + k - 2*x*(k+1)*(k+5)/G(k+1); (continued fraction). - Sergei N. Gladkovskii, Apr 09 2013
G.f.: G(0)/(2*(1-x^2)*(1-x)), where G(k)= 1 + 1/(1 - x*(k+1)/(x*(k+2) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, May 25 2013
a(n) = Sum_{k=0..floor((n+1)/2)} (-2)^k*binomial(n+1-2k,k+1), n>=0. - Taras Goy, Apr 15 2020
MATHEMATICA
LinearRecurrence[{2, -1, -2, 2}, {1, 2, 3, 2}, 50] (* Harvey P. Dale, Jul 28 2019 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, Nov 17 2002
STATUS
approved