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 A333511 Number of self-avoiding walks in the n X 3 grid graph which start at any of the n vertices on left side of the graph and terminate at any of the n vertices on the right side. 3
 1, 16, 95, 426, 1745, 6838, 25897, 95292, 342505, 1208392, 4201765, 14445130, 49221691, 166563454, 560595853, 1878809676, 6275993883, 20910561068 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..18. EXAMPLE a(1) = 1; +--*--+ a(2) = 16; + *--+ + * + +--* + +--*--+ | | | | | | *--* * *--*--* * *--* * * * ------------------------------------- + *--* + * * +--* * +--*--* | | | | | | *--* + *--*--+ * *--+ * * + ------------------------------------- *--* + *--*--+ * *--+ * * + | | | | | | + *--* + * * +--* * +--*--* ------------------------------------- *--* * *--*--* * *--* * * * | | | | | | + *--+ + * + +--* + +--*--+ PROG (Python) # Using graphillion from graphillion import GraphSet import graphillion.tutorial as tl def A(start, goal, n, k): universe = tl.grid(n - 1, k - 1) GraphSet.set_universe(universe) paths = GraphSet.paths(start, goal) return paths.len() def A333509(n, k): if n == 1: return 1 s = 0 for i in range(1, n + 1): for j in range(k * n - n + 1, k * n + 1): s += A(i, j, k, n) return s def A333511(n): return A333509(n, 3) print([A333511(n) for n in range(1, 15)]) CROSSREFS Column k=3 of A333509. Sequence in context: A159245 A066487 A318021 * A320406 A241936 A321338 Adjacent sequences: A333508 A333509 A333510 * A333512 A333513 A333514 KEYWORD nonn AUTHOR Seiichi Manyama, Mar 25 2020 STATUS approved

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Last modified April 22 18:29 EDT 2024. Contains 371906 sequences. (Running on oeis4.)