

A321038


Number of words of length 3n such that all letters of the octonary alphabet occur at least once and are introduced in ascending order and which can be built by repeatedly inserting triples of identical letters into the initially empty word.


2



43263, 7104240, 694377450, 52825297536, 3463906615356, 206132702914710, 11470240358743842, 608199451197152100, 31120996552066805175, 1550313320809537870320, 75665062766954753664390, 3635046065217379316477688, 172499755061750807257325550
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OFFSET

8,1


LINKS

Alois P. Heinz, Table of n, a(n) for n = 8..602


MAPLE

b:= (n, k)> `if`(n=0, 1, k/n*add(binomial(3*n, j)*(nj)*(k1)^j, j=0..n1)):
a:= n> (k> add((1)^i*b(n, ki)/(i!*(ki)!), i=0..k))(8):
seq(a(n), n=8..25);


CROSSREFS

Column k=8 of A256311.
Sequence in context: A238595 A205053 A146074 * A256767 A258677 A184382
Adjacent sequences: A321035 A321036 A321037 * A321039 A321040 A321041


KEYWORD

nonn


AUTHOR

Alois P. Heinz, Oct 26 2018


STATUS

approved



