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A018840
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Number of steps for {2,3} fairy knight to reach (n,0) on infinite chessboard.
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2
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0, 5, 4, 5, 2, 5, 2, 5, 4, 5, 4, 7, 4, 5, 6, 7, 6, 7, 6, 7, 8, 9, 8, 9, 8, 9, 10, 11, 10, 11, 10, 11, 12, 13, 12, 13, 12, 13, 14, 15, 14, 15, 14, 15, 16, 17, 16, 17, 16, 17, 18, 19, 18, 19, 18, 19, 20, 21, 20, 21, 20, 21, 22, 23, 22, 23, 22, 23, 24, 25, 24, 25, 24, 25, 26, 27, 26, 27, 26, 27
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OFFSET
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0,2
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COMMENTS
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Apparently also the minimum number of moves of the (1,5)-leaper to reach (n,n) starting from (0,0). - R. J. Mathar, Jan 05 2018
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LINKS
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FORMULA
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G.f.: x*(5 - x + x^2 - 3*x^3 + 3*x^4 - 3*x^5 - 2*x^6 + 2*x^9 - 2*x^12 + 2*x^13 - 2*x^16 + 2*x^17) / ((1 - x)^2*(1 + x)*(1 - x + x^2)*(1 + x + x^2)).
a(n) = a(n-1) + a(n-6) - a(n-7) for n>7.
(End)
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PROG
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(PARI) concat(0, Vec(x*(5 - x + x^2 - 3*x^3 + 3*x^4 - 3*x^5 - 2*x^6 + 2*x^9 - 2*x^12 + 2*x^13 - 2*x^16 + 2*x^17) / ((1 - x)^2*(1 + x)*(1 - x + x^2)*(1 + x + x^2)) + O(x^100))) \\ Colin Barker, Dec 28 2017
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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