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 A336705 Coordination sequence for the half-Manhattan lattice. 2
 1, 3, 7, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144, 148, 152, 156, 160, 164, 168, 172, 176, 180, 184, 188, 192, 196, 200, 204, 208, 212, 216, 220, 224, 228 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS In the half-Manhattan lattice, E-W streets run alternately E and W, but N-S streets are two way. LINKS Table of n, a(n) for n=0..57. Sean A. Irvine, Illustration of a(0) to a(7) FORMULA G.f.: (1+x) * (1+2*x^2-x^3) / (1-x)^2. a(n) = 4*n, n >= 3. CROSSREFS Cf. A336627 (Manhattan lattice), A008574 (square lattice), A336726 (self-avoiding walks), A336742 (self-avoiding cycles). Sequence in context: A160998 A141205 A310237 * A310238 A299638 A189474 Adjacent sequences: A336702 A336703 A336704 * A336706 A336707 A336708 KEYWORD nonn AUTHOR Sean A. Irvine, Jul 31 2020 STATUS approved

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Last modified June 2 07:25 EDT 2023. Contains 363081 sequences. (Running on oeis4.)