OFFSET
0,5
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
M. H. Albert, M. D. Atkinson and Robert Brignall, The enumeration of three pattern classes, arXiv:1206.3183 [math.CO], (2012), p. 14 (Lemma 4.3).
Index entries for linear recurrences with constant coefficients, signature (3,0,-4).
FORMULA
G.f.: x^4*(2-3*x-x^2)/((1+x)*(1-2*x)^2).
a(n) = (2^(n-5)*(3*n+16)+4*(-1)^n)/9 with n>3, a(0)=a(1)=a(2)=a(3)=0. [Bruno Berselli, Nov 29 2012]
MATHEMATICA
CoefficientList[Series[x^4 (2 - 3 x - x^2)/((1 + x) (1 - 2 x)^2), {x, 0, 35}], x] (* Bruno Berselli, Nov 30 2012 *)
PROG
(Maxima) makelist(coeff(taylor(x^4*(2-3*x-x^2)/((1+x)*(1-2*x)^2), x, 0, n), x, n), n, 0, 35); /* Bruno Berselli, Nov 29 2012 */
(Magma) I:=[0, 0, 0, 0, 2, 3, 8]; [n le 7 select I[n] else 3*Self(n-1) - 4*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Dec 14 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 28 2012
STATUS
approved