A218130 Number of length 6 primitive (=aperiodic or period 6) n-ary words.

0, 0, 54, 696, 4020, 15480, 46410, 117264, 261576, 530640, 998910, 1770120, 2984124, 4824456, 7526610, 11387040, 16772880, 24132384, 34006086, 47038680, 63991620, 85756440, 113368794, 148023216, 191088600, 244124400, 308897550, 387400104, 481867596, 594798120

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (7, -21, 35, -35, 21, -7, 1).

Formula

G.f.: -6*x^2*(9+53*x+47*x^2+11*x^3)/(x-1)^7.

a(n) = n^6-n^3-n^2+n.

Maple

a:= n-> (((n^3-1)*n-1)*n+1)*n:
seq(a(n), n=0..30);

Mathematica

Table[n^6-n^3-n^2+n, {n, 0, 30}] (* or *) LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 0, 54, 696, 4020, 15480, 46410}, 30] (* Harvey P. Dale, Oct 13 2017 *)

Crossrefs

Row n=6 of A143324.

Sequence in context: A193152 A253006 A128961 * A321635 A090835 A069980

Adjacent sequences: A218127 A218128 A218129 * A218131 A218132 A218133

Keyword

nonn,easy

Author

Alois P. Heinz, Oct 21 2012

Status

approved