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 A018841 Number of steps for {2,3} fairy knight to reach (n,n) on infinite chessboard. 1
 0, 2, 4, 6, 4, 2, 4, 6, 6, 6, 4, 6, 6, 6, 8, 6, 8, 8, 8, 10, 8, 10, 10, 10, 12, 10, 12, 12, 12, 14, 12, 14, 14, 14, 16, 14, 16, 16, 16, 18, 16, 18, 18, 18, 20, 18, 20, 20, 20, 22, 20, 22, 22, 22, 24, 22, 24, 24, 24, 26, 24, 26, 26, 26, 28, 26, 28, 28, 28, 30, 28, 30, 30, 30, 32, 30, 32, 32 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Colin Barker, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1). FORMULA For n >= 14, a(n) = a(n-5) + 2. - David W. Wilson From Colin Barker, Jan 04 2018: (Start) G.f.: 2*x*(1 + x + x^2 - x^3 - x^4 - x^7 + x^8 - x^11 + x^13) / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4)). a(n) = a(n-1) + a(n-5) - a(n-6) for n>5. (End) PROG (PARI) concat(0, Vec(2*x*(1 + x + x^2 - x^3 - x^4 - x^7 + x^8 - x^11 + x^13) / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4)) + O(x^40))) \\ Colin Barker, Jan 04 2018 CROSSREFS Sequence in context: A072984 A317310 A231655 * A182043 A138125 A098793 Adjacent sequences:  A018838 A018839 A018840 * A018842 A018843 A018844 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified July 4 12:18 EDT 2020. Contains 335448 sequences. (Running on oeis4.)