OFFSET
0,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..158 (terms 1..28 from R. J. Mathar)
R. J. Mathar, A class of multinomial permutations avoiding object clusters, vixra:1511.0015 (2015), sequence M_{c,4}/c!.
FORMULA
From Vaclav Kotesovec, Nov 24 2018: (Start)
Recurrence: 3*(64*n^3 - 280*n^2 + 414*n - 245)*a(n) = (2048*n^6 - 12032*n^5 + 30400*n^4 - 42608*n^3 + 32484*n^2 - 14624*n + 1731)*a(n-1) + 3*(3840*n^5 - 20640*n^4 + 40104*n^3 - 36340*n^2 + 23378*n - 13429)*a(n-2) - 18*(384*n^4 - 1488*n^3 + 1556*n^2 - 986*n + 649)*a(n-3) - 27*(64*n^3 - 88*n^2 + 46*n - 47)*a(n-4).
a(n) ~ 2^(5*n+1) * n^(3*n) / (3^n * exp(3*n + 3)). (End)
EXAMPLE
Some solutions for n=3:
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
3 1 3 3 1 3 3 3 3 3 3 1 1 3 1 1
1 2 2 2 2 2 2 1 1 2 1 3 3 1 3 2
2 3 3 3 1 1 3 2 2 3 2 1 2 3 1 1
3 2 1 2 3 2 1 3 1 1 3 2 3 2 2 3
1 3 2 3 2 3 3 1 3 2 2 3 2 1 3 1
3 2 3 1 3 1 2 3 1 1 1 2 1 3 2 3
1 1 1 3 1 3 1 2 2 3 3 3 2 2 3 2
2 3 2 1 3 2 3 1 3 1 1 2 3 3 1 3
3 1 1 2 2 3 1 3 2 2 2 3 1 1 3 2
2 3 3 1 3 1 2 2 3 3 3 1 3 2 2 3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 21 2011
EXTENSIONS
a(0)=1 prepended by Seiichi Manyama, Nov 16 2018
STATUS
approved