login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A321036 Number of words of length 3n such that all letters of the senary 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
1428, 122094, 6577494, 288152280, 11263151718, 410775452736, 14329297278912, 485304167135463, 16110681501126303, 527563895500327686, 17115058041339933282, 551744934193726332360, 17712851478876415128930, 567151641983253355425936, 18132410018268844312487352 (list; graph; refs; listen; history; text; internal format)
OFFSET

6,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 6..659

MAPLE

b:= (n, k)-> `if`(n=0, 1, k/n*add(binomial(3*n, j)*(n-j)*(k-1)^j, j=0..n-1)):

a:= n-> (k-> add((-1)^i*b(n, k-i)/(i!*(k-i)!), i=0..k))(6):

seq(a(n), n=6..25);

CROSSREFS

Column k=6 of A256311.

Sequence in context: A260283 A156853 A292704 * A094230 A238136 A060364

Adjacent sequences:  A321033 A321034 A321035 * A321037 A321038 A321039

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 26 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 20 20:50 EST 2021. Contains 340332 sequences. (Running on oeis4.)