A234267 - OEIS

A234267

Expansion of (1-x)/((1-2*x)*(1-5*x+6*x^2-x^3)).

1, 6, 26, 99, 353, 1213, 4078, 13529, 44518, 145750, 475683, 1549457, 5040985, 16387962, 53251549, 172987342, 561848146, 1824633763, 5925198353, 19240299477, 62475465318, 202861776657, 658698488006, 2138801439710, 6944686435779, 22549338805857, 73217410408753, 237735772753266, 771923874337397

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OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

T. Mansour and M. Shattuck, Some enumerative results related to ascent sequences, arXiv preprint arXiv:1207.3755 [math.CO], 2012. Also Discrete Math., 315-316 (2013), 29-41. See Lemma A.2.

Index entries for linear recurrences with constant coefficients, signature (7,-16,13,-2).

FORMULA

G.f.: (1-x)/((1-2*x)*(1-5*x+6*x^2-x^3)).

a(n) = 7*a(n-1)-16*a(n-2)+13*a(n-3)-2*a(n-4) for n>3, a(0)=1, a(1)=6, a(2)=26, a(3)=99. - Philippe Deléham, Dec 25 2013

MATHEMATICA

CoefficientList[Series[(1 - x)/((1 - 2 x) (1 - 5 x + 6 x^2 - x^3)), {x, 0, 40}], x] (* Vincenzo Librandi, Apr 28 2014 *)

PROG

(Magma) I:=[1, 6, 26, 99]; [n le 4 select I[n] else 7*Self(n-1)-16*Self(n-2)+13*Self(n-3)-2*Self(n-4): n in [1..30]]; // Vincenzo Librandi, Apr 28 2014

CROSSREFS

Sequence in context: A239179 A307309 A186314 * A055420 A137746 A344504

Adjacent sequences: A234264 A234265 A234266 * A234268 A234269 A234270

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Dec 23 2013

STATUS

approved