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 A223481 Rolling icosahedron face footprints: number of 3 X n 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. 1
 400, 243, 2025, 16875, 147825, 1296675, 11374425, 99776475, 875239425, 7677601875, 67347938025, 590776238475, 5182290270225, 45459059955075, 398766959055225, 3497984511586875, 30684326686171425, 269162971152369075 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 3 of A223480. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 9*a(n-1) - 2*a(n-2) for n>4. Empirical g.f.: x*(400 - 3357*x + 638*x^2 - 864*x^3) / (1 - 9*x + 2*x^2). - Colin Barker, Aug 20 2018 EXAMPLE Some solutions for n=3: ..0..2..3....0..1..0....0..2..8....0..5..0....0..1..0....0..2..0....0..1..6 ..3..4..1....0..2..8....3..2..8....0..5..9....0..2..0....3..2..3....6..1..6 ..1..4..1....8..2..8....8..9..5....9..8..2....3..2..8....3..4..1....6.10.12 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 CROSSREFS Cf. A223480. Sequence in context: A356821 A223284 A061042 * A037991 A200837 A250847 Adjacent sequences: A223478 A223479 A223480 * A223482 A223483 A223484 KEYWORD nonn AUTHOR R. H. Hardin, Mar 20 2013 STATUS approved

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Last modified May 29 04:03 EDT 2023. Contains 363029 sequences. (Running on oeis4.)