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A211386
Expansion of 1/((1-2*x)^5*(1-x)).
3
1, 11, 71, 351, 1471, 5503, 18943, 61183, 187903, 553983, 1579007, 4374527, 11829247, 31326207, 81461247, 208470015, 525991935, 1310457855, 3228041215, 7870611455, 19012780031, 45541752831, 108246597631, 255466668031, 598980165631, 1395931480063, 3235049897983
OFFSET
0,2
COMMENTS
Occurs in the enumerations of inflations of code words babxxxdc [Albert et al. Sec 5.5.1]
LINKS
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.
Harry Crane, Left-right arrangements, set partitions, and pattern avoidance, Australasian Journal of Combinatorics, 61(1) (2015), 57-72.
FORMULA
a(n) = 2^n*(24+18*n+23*n^2+6*n^3+n^4)/12-1.
a(0)=1, a(1)=11, a(2)=71, a(3)=351, a(4)=1471, a(5)=5503, a(n)=11*a(n-1)- 50*a(n-2)+ 120*a(n-3)-160*a(n-4)+112*a(n-5)-32*a(n-6). - Harvey P. Dale, Mar 02 2015
MATHEMATICA
CoefficientList[Series[1/((1-2x)^5(1-x)), {x, 0, 30}], x] (* or *) LinearRecurrence[ {11, -50, 120, -160, 112, -32}, {1, 11, 71, 351, 1471, 5503}, 30] (* Harvey P. Dale, Mar 02 2015 *)
PROG
(PARI) Vec(1/((1-2*x)^5*(1-x))+ O(x^30)) \\ Michel Marcus, Feb 12 2015
CROSSREFS
Cf. A003472 (first differences).
Sequence in context: A174822 A201790 A268985 * A049350 A164559 A319535
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Feb 07 2013
STATUS
approved