A271615 Number of ways to reciprocally link elements of an n X n X n triangular array with themselves or a neighbor, with no more than 6 elements linked to themselves.

1, 4, 27, 406, 7764, 222936, 18314708, 1182352612, 30892003921, 3065366376540, 2070868688611599, 493143363040812884, 25923218026065797712, 11188107558636007931696, 60230981411511158858617306, 63827420909748305015725846472, 9319830273030294425399538816052

Offset

1,2

Comments

Column 6 of A271617.

Links

Table of n, a(n) for n=1..17.

Example

Some solutions for n=4
.....0........6........0........6........6........6........0........0
....6.0......0.1......5.0......0.1......0.1......0.1......0.0......0.0
...5.1.5....5.0.0....2.0.6....5.0.6....5.4.3....4.3.6....5.4.3....5.6.6
..2.0.2.0..2.4.3.0..0.4.3.1..2.0.0.1..2.0.4.3..0.0.0.1..2.0.0.0..2.0.1.1
Element moves: 0=itself 1=nw 2=ne 3=w 4=e 5=sw 6=se, reciprocals total 7

Crossrefs

Cf. A271617.

Sequence in context: A334527 A104169 A359904 * A271616 A123672 A269869

Adjacent sequences: A271612 A271613 A271614 * A271616 A271617 A271618

Keyword

nonn

Author

R. H. Hardin, Apr 10 2016

Extensions

a(14)-a(17) from Alois P. Heinz, Jun 15 2017

Status

approved