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A271897 Expansion of ( 1-2*x+3*x^2 ) / ( 1-4*x+5*x^2-4*x^3 ). 2
1, 2, 6, 18, 50, 134, 358, 962, 2594, 6998, 18870, 50866, 137106, 369574, 996230, 2685474, 7239042, 19513718, 52601558, 141793810, 382222322, 1030326470, 2777369510, 7486734978, 20181398242, 54401396118, 146645533174, 395300745074, 1065580898898, 2872402002918, 7742906497478, 20871939570914 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Sum of all second elements at level n of the TRIP-Stern sequence corresponding to the permutation triple (e,e,e)

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Ilya Amburg, Krishna Dasaratha, Laure Flapan, Thomas Garrity, Chansoo Lee, Cornelia Mihaila, Nicholas Neumann-Chun, Sarah Peluse, Matthew Stoffregen, Stern Sequences for a Family of Multidimensional Continued Fractions: TRIP-Stern Sequences, arXiv:1509.05239 [math.CO], 2015, Section 7.2.1.

Alice L. L. Gao, Sergey Kitaev, On partially ordered patterns of length 4 and 5 in permutations, arXiv:1903.08946 [math.CO], 2019.

Index entries for linear recurrences with constant coefficients, signature (4,-5,4).

MATHEMATICA

CoefficientList[Series[(1-2x+3x^2)/(1-4x+5x^2-4x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{4, -5, 4}, {1, 2, 6}, 40] (* Harvey P. Dale, Dec 27 2016 *)

PROG

(PARI) x='x+O('x^99); Vec((1-2*x+3*x^2)/(1-4*x+5*x^2-4*x^3)) \\ Altug Alkan, Apr 16 2016

CROSSREFS

Cf. A000930 (maximum at level n).

Sequence in context: A062026 A048495 A089380 * A304962 A180282 A081154

Adjacent sequences:  A271894 A271895 A271896 * A271898 A271899 A271900

KEYWORD

nonn,easy

AUTHOR

R. J. Mathar, Apr 16 2016

STATUS

approved

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Last modified May 25 22:17 EDT 2019. Contains 323576 sequences. (Running on oeis4.)