A223206 Rolling icosahedron face footprints: number of nX5 0..19 arrays starting with 0 where 0..19 label faces of an icosahedron and every array movement to a horizontal or vertical neighbor moves across an icosahedral edge.
81, 1875, 50553, 1412907, 39868737, 1127761923, 31921015497, 903661481115, 25583075832465, 724276345970163, 20504869741550745, 580510427181846027, 16434750355138945761, 465281963351360897763, 13172534004090254190441
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..1..4..3..4....0..2..0..2..0....0..1..0..2..3....0..2..0..1..6 ..1..4..3..4..1....2..8..2..0..2....5..0..5..0..2....1..0..1..4..1 ..4..1..4..1..6....8..2..3..2..3....0..2..0..5..0....0..1..4..1..4 Face neighbors: 0 -> 1 2 5 1 -> 0 4 6 2 -> 0 3 8 3 -> 2 4 16 4 -> 3 1 17 5 -> 0 7 9 6 -> 1 7 10 7 -> 6 5 11 8 -> 2 9 13 9 -> 8 5 14 10 -> 6 12 17 11 -> 7 12 14 12 -> 11 10 19 13 -> 8 15 16 14 -> 9 11 15 15 -> 14 13 19 16 -> 3 13 18 17 -> 4 10 18 18 -> 16 17 19 19 -> 15 18 12
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 31*a(n-1) -24*a(n-2) -1612*a(n-3) +3816*a(n-4) +1152*a(n-5) -2784*a(n-6) +256*a(n-7)
Comments