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 A177238 Number of n-step self-avoiding walks on square lattice plus number of n-step self-avoiding walks on hexagonal [ =triangular ] lattice. 0
 2, 10, 42, 174, 718, 3014, 12726, 54054, 230046, 980402, 4177266, 17789230, 75680138, 321616186, 1365165694, 5788182178, 24514575654, 103720434558, 438421398326, 1851566492994, 7813337317842, 32946701361962, 138832416613530 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(0) = 2 is the only prime in the sequence. (By symmetry in both lattices, we are adding two sequences with even terms if n>0.)  a(n) is semiprime for a(1) = 10 = 2 * 5, a(4) = 718 = 2 * 359, a(9) = 980402 = 2 * 490201. The Jensen table linked from A001334 should allow extension through a(40). LINKS FORMULA a(n) = A001334(n) + A001411(n). EXAMPLE n\Triangle | Square | Sum 0          1     1     2 1          6     4     10 2          30    12    42 3          138   36    174 4          618   100   718 5          2730  284   3014 6          11946 780   12726 CROSSREFS Cf. A001334, A001411. Sequence in context: A302524 A084180 A020988 * A084480 A309182 A099553 Adjacent sequences:  A177235 A177236 A177237 * A177239 A177240 A177241 KEYWORD nonn,walk AUTHOR Jonathan Vos Post, Dec 11 2010 STATUS approved

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Last modified December 6 04:14 EST 2019. Contains 329784 sequences. (Running on oeis4.)