login
A190927
Number of permutations of n copies of 1..7 introduced in order 1..7 with no element equal to another within a distance of 1.
8
1, 47844, 4420321081, 551248360550999, 81644850343968535401, 13519747358522016160671387, 2421032324142610480402567434373, 459408385876250801291447710561829082, 91155245844064069307740171414201519055298
OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..185 (terms 1..25 from R. H. Hardin)
FORMULA
a(n) ~ 343 * sqrt(7) * 2^(7*n-8) * 3^(7*n-3) / (625 * Pi^3 * n^3). - Vaclav Kotesovec, Nov 24 2018
EXAMPLE
Some solutions for n=2:
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 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
4 4 4 4 4 2 2 4 4 4 2 4 4 4 4 2
5 5 5 1 5 4 4 2 5 5 4 2 1 3 2 1
6 6 6 5 6 5 3 5 3 6 5 4 4 5 5 4
2 7 4 6 7 6 5 6 6 3 6 5 5 6 6 5
7 3 5 4 2 3 6 5 7 7 7 1 6 4 4 6
5 4 2 2 1 5 7 6 2 6 3 6 7 5 7 7
6 5 6 3 6 4 5 1 4 1 7 3 2 7 1 3
4 6 1 5 7 7 7 3 7 7 5 7 5 2 7 4
3 2 7 7 5 1 1 7 1 5 1 6 7 1 5 6
7 7 3 6 4 6 6 4 5 4 6 5 6 7 6 7
1 1 7 7 3 7 4 7 6 2 4 7 3 6 3 5
CROSSREFS
Column k=7 of A322013.
Cf. A000012 (b=2), A190917 (b=3), A190918 (b=4), A190920 (b=5), A190923 (b=6), A190932 (b=8), A321987 (b=9).
Sequence in context: A254800 A254807 A253816 * A251455 A204402 A203929
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 23 2011
STATUS
approved