OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
M. H. Albert, M. D. Atkinson, R. Brignall, The enumeration of three pattern classes using monotone grid classes, El. J. Combinat. 19 (3) (2012) P20. Section 5.5.1
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 (13,-72,220,-400,432,-256,64).
FORMULA
a(n) = 1 + 2^(n-2)*n*(n^4 + 10*n^3 + 55*n^2 + 110*n + 184)/15. - Bruno Berselli, Feb 08 2013
A211386(n) = a(n) - 2*a(n-1). - R. J. Mathar, Feb 08 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 2 x)^6 (1 - x)), {x, 0, 30}], x] (* Vincenzo Librandi, Sep 10 2013 *)
LinearRecurrence[{13, -72, 220, -400, 432, -256, 64}, {1, 13, 97, 545, 2561, 10625, 40193}, 30] (* Harvey P. Dale, Sep 01 2023 *)
PROG
(Magma) m:=24; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-2*x)^6*(1-x)))); // Bruno Berselli, Feb 08 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Feb 07 2013
STATUS
approved