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A018842
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Number of squares on infinite chess-board at n knight's moves from center.
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3
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1, 8, 32, 68, 96, 120, 148, 176, 204, 232, 260, 288, 316, 344, 372, 400, 428, 456, 484, 512, 540, 568, 596, 624, 652, 680, 708, 736, 764, 792, 820, 848, 876, 904, 932, 960, 988, 1016, 1044, 1072, 1100, 1128, 1156
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Mordechai Katzman, Knight's moves on an infinite board
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FORMULA
| a(n) = 28*n+8, n >= 4.
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MAPLE
| (1+5*x+12*x^2-8*x^4+4*x^5)*(1+x)/(1-x)^2;
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MATHEMATICA
| CoefficientList[Series[(1+5x+12x^2-8x^4+4x^5)(1+x)/(1-x)^2, {x, 0, 50}], x] (* or *) Join[{1, 8, 32, 68, 96}, LinearRecurrence[{2, -1}, {120, 148}, 46]] (* From Harvey P. Dale, July 05 2011 *)
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CROSSREFS
| Cf. A018836, A038522.
Sequence in context: A005879 A067519 A009245 * A139098 A130809 A018839
Adjacent sequences: A018839 A018840 A018841 * A018843 A018844 A018845
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KEYWORD
| nonn,nice,walk,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Marc LeBrun (mlb(AT)well.com)
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