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A194717 Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting five doublets into the initially empty word. 2
0, 1, 126, 1181, 4966, 14289, 32966, 65821, 118686, 198401, 312814, 470781, 682166, 957841, 1309686, 1750589, 2294446, 2956161, 3751646, 4697821, 5812614, 7114961, 8624806, 10363101, 12351806, 14613889, 17173326, 20055101, 23285206, 26890641, 30899414, 35340541 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

FORMULA

G.f.: -x*(1+121*x+561*x^2+311*x^3+14*x^4) / (x-1)^5.

a(0) = 0, a(n) = 1+(8+(27+(48+42*(n-1))*(n-1))*(n-1))*(n-1) for n>0.

EXAMPLE

a(1) = 1: aaaaaaaaaa (with 1-ary alphabet {a}).

MAPLE

a:= n-> `if`(n=0, 0, (x-> 1+(8+(27+(48+42*x)*x)*x)*x)(n-1)):

seq(a(n), n=0..40);

CROSSREFS

Row n=5 of A183134.

Sequence in context: A104678 A154093 A172139 * A002953 A216588 A297657

Adjacent sequences:  A194714 A194715 A194716 * A194718 A194719 A194720

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Sep 02 2011

STATUS

approved

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Last modified November 30 17:31 EST 2020. Contains 338807 sequences. (Running on oeis4.)