A223477 Rolling icosahedron face footprints: number of n X 5 0..19 arrays starting with 0 where 0..19 label faces of an icosahedron and every array movement to a horizontal or antidiagonal neighbor moves across an icosahedral edge.
81, 3375, 147825, 6526575, 288507825, 12755926575, 563999907825, 24937217326575, 1102598111307825, 48751338478726575, 2155538829022707825, 95307078736540126575, 4213999366856734107825, 186321844088731401526575
Offset: 1
Keywords
Examples
Some solutions for n=3: ..0..1..6.10.17....0..1..6..7..5....0..2..0..2..0....0..2..0..1..6 ..6.10.17.10.12....6..7.11..7..6....8..2..0..5..7....0..1..0..1..4 .17.10.12.11.12....6..7..5..7..5....0..5..7.11.14....0..5..0..1..6 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
Crossrefs
Cf. A223480.
Formula
Empirical: a(n) = 51*a(n-1) - 300*a(n-2).
Empirical g.f.: 27*x*(3 - 28*x) / (1 - 51*x + 300*x^2). - Colin Barker, Aug 20 2018
Comments