A211387 Expansion of x*(1 -15*x +99*x^2 -373*x^3 +879*x^4 -1338*x^5 +1311*x^6 -804*x^7 +289*x^8 -44*x^9) / [(1-3*x+x^2) *(1-2*x)^6 *(1-x)^2].

1, 2, 5, 17, 69, 286, 1137, 4277, 15247, 51786, 168566, 528740, 1606023, 4744071, 13678697, 38620692, 107073080, 292195582, 786536753, 2092318473, 5509620835, 14382935710, 37272512506, 96000674264, 246029006363, 628007115019, 1598123382173, 4057780889704

Offset

1,2

Comments

Appears in the enumeration of {1324,4312}-avoiding permutations. [Albert et al., Section 5.7]

Links

Table of n, a(n) for n=1..28.

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.

Index entries for linear recurrences with constant coefficients, signature (17,-128,561,-1581,2984,-3804,3216,-1712,512,-64).

Formula

a(n) = -21 -5*n +2^n*(267/16 +n^4/128 -161*n^3/768 +229*n^2/128 -451*n/40 +n^5/3840) +A001519(n+3).

Crossrefs

Sequence in context: A239201 A027361 A101971 * A372376 A303952 A162037

Adjacent sequences: A211384 A211385 A211386 * A211388 A211389 A211390

Keyword

nonn,easy

Author

R. J. Mathar, Feb 07 2013

Status

approved