A321041 Number of words of length 6n such that all letters of the n-ary 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.
1, 1, 97, 29886, 16482191, 13337746758, 14329297278912, 19256258184412314, 31120996552066805175, 58830559749207291469515, 127426007577261157375345878, 311250333529456439224989700168, 846594239519776323268829614117536, 2538054216720547203941994076323844425
Offset: 0
Keywords
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..230
Crossrefs
Cf. A256311.
Formula
a(n) = A256311(2n,n).