login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

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