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 A333515 Number of self-avoiding closed paths on an n X 5 grid which pass through four corners ((0,0), (0,4), (n-1,4), (n-1,0)). 3
 1, 7, 49, 373, 3105, 26515, 227441, 1953099, 16782957, 144262743, 1240194297, 10662034451, 91663230249, 788046822891, 6775004473757, 58246174168047, 500755017859261, 4305100014182879, 37011883913816129, 318199242452585915, 2735628331213604009, 23518793814422304163 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS Also number of self-avoiding closed paths on a 5 X n grid which pass through four corners ((0,0), (0,n-1), (4,n-1), (4,0)). LINKS Seiichi Manyama, Table of n, a(n) for n = 2..1000 EXAMPLE a(2) = 1; +--*--*--*--+ | | +--*--*--*--+ a(3) = 7; +--*--*--*--+ +--*--*--*--+ +--*--*--*--+ | | | | | | * *--* * * *--*--* * * *--* * | | | | | | | | | | | | +--*--* *--+ +--* *--+ +--* *--*--+ +--*--*--*--+ +--*--* *--+ +--* *--*--+ | | | | | | | | | | * * * *--* * * *--* * | | | | | | +--*--*--*--+ +--*--*--*--+ +--*--*--*--+ +--* *--+ | | | | * *--*--* * | | +--*--*--*--+ PROG (Python) # Using graphillion from graphillion import GraphSet import graphillion.tutorial as tl def A333513(n, k): universe = tl.grid(n - 1, k - 1) GraphSet.set_universe(universe) cycles = GraphSet.cycles() for i in [1, k, k * (n - 1) + 1, k * n]: cycles = cycles.including(i) return cycles.len() def A333515(n): return A333513(n, 5) print([A333515(n) for n in range(2, 25)]) CROSSREFS Column k=5 of A333513. Sequence in context: A344270 A144820 A344251 * A324353 A349781 A199554 Adjacent sequences: A333512 A333513 A333514 * A333516 A333517 A333518 KEYWORD nonn AUTHOR Seiichi Manyama, Mar 25 2020 STATUS approved

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Last modified February 3 01:46 EST 2023. Contains 360024 sequences. (Running on oeis4.)