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A027608 Expansion of 1/((1-x)*(1-2x)^4). 7
1, 9, 49, 209, 769, 2561, 7937, 23297, 65537, 178177, 471041, 1216513, 3080193, 7667713, 18808833, 45547521, 109051905, 258473985, 607125505, 1414529025, 3271557121, 7516192769, 17163091969 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..22.

M. H. Albert, M. D. Atkinson, R. Brignall, The enumeration of three pattern classes using monotone grid classes, E. J. Combinat. 19 (3) (2012) P20. Chapter 5.5.1 (with leading zeros).

Harry Crane, Left-right arrangements, set partitions, and pattern avoidance, Australasian Journal of Combinatorics, 61(1) (2015), 57-72.

Index entries for linear recurrences with constant coefficients, signature (9,-32,56,-48,16).

FORMULA

a(n-1) = 1 + (n-1)*2^(n+1) + ((n^3 - 7*n + 6)*2^(n-1))/3, n >= 1. - Roger Voles, Dec 07 2004, index corrected by R. J. Mathar, Mar 14 2011

a(n) = A119258(n+4,n). - Reinhard Zumkeller, May 11 2006

a(n) = 1 + n*2^(n+2) + (((n+1)^3 - 7*(n+1) + 6)*2^n)/3 = (n/3)*(n^2 + 3n + 8) 2^n + 1, n >= 0. - Daniel Forgues, Nov 01 2012

PROG

(PARI) Vec(1/((1-x)*(1-2*x)^4)+O(x^99)) \\ Charles R Greathouse IV, Sep 23 2012

CROSSREFS

Cf. A001789 (first differences).

Sequence in context: A082608 A058031 A228212 * A003297 A012248 A080026

Adjacent sequences:  A027605 A027606 A027607 * A027609 A027610 A027611

KEYWORD

nonn,easy,changed

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 27 13:18 EST 2020. Contains 332306 sequences. (Running on oeis4.)