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 A221441 Hilltop maps: number of n X 3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..1 n X 3 array. 1
 5, 33, 221, 1473, 9829, 65569, 437437, 2918273, 19468741, 129882145, 866485149, 5780598081, 38564209189, 257274109985, 1716357449085, 11450366664449, 76389039372165, 509615587618849, 3399807737852509, 22681199192442049 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A221446. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 5*a(n-1) + 11*a(n-2) + a(n-3). Empirical g.f.: x*(5 + 8*x + x^2) / (1 - 5*x - 11*x^2 - x^3). - Colin Barker, Aug 05 2018 EXAMPLE Some solutions for n=3: ..1..1..0....0..1..1....1..0..1....0..1..1....1..0..1....1..1..0....0..1..1 ..0..0..1....0..1..0....1..1..1....0..1..0....0..1..0....0..1..1....1..1..1 ..1..1..0....1..1..1....1..1..0....1..0..1....0..1..1....1..0..1....1..0..1 CROSSREFS Cf. A221446. Sequence in context: A250163 A164538 A197533 * A083076 A361237 A162816 Adjacent sequences: A221438 A221439 A221440 * A221442 A221443 A221444 KEYWORD nonn AUTHOR R. H. Hardin, Jan 17 2013 STATUS approved

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Last modified June 17 08:51 EDT 2024. Contains 373444 sequences. (Running on oeis4.)