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Search: id:A055607
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| 0, 0, 2, 4, 7, 10, 14, 19, 24, 30, 36, 44, 51, 60, 68, 79, 88, 100, 110, 124, 135, 150, 162, 179, 192, 210, 224, 244, 259, 280, 296, 319, 336, 360, 378, 404, 423, 450, 470, 499, 520, 550, 572, 604, 627, 660, 684, 719, 744, 780, 806, 844, 871, 910, 938, 979, 1008
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Consider an n X n chessboard. Place n queens in the cells of the first row, in cells (1,1), (2,1),..., (n,1) and [(n+1)/2] pawns in the odd cells of the second row, namely in cells (1,2), (3,2), (5,2), ... Which is the number of the unattacked (by the queens) cells ? How many cells are not attacked by the queens?
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REFERENCES
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Suggested by a chess-board problem from Antreas P. Hatzipolakis.
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FORMULA
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G.f. x^3(x^4-x^3-x^2-2x-2)/(x-1)^3/(x+1)^2/(x^2+1). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jul 25 2003
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MAPLE
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f := [0, 0]: for i from 3 by 2 to 60 do f := [op(f), ((i-1)/2)^2 - 1 + floor((i-1)/4)*ceil((i-1)/4)]: f := [op(f), f[nops(f)] + (i+1)/2]: od: f;
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CROSSREFS
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Adjacent sequences: A055604 A055605 A055606 this_sequence A055608 A055609 A055610
Sequence in context: A145106 A127723 A076268 this_sequence A024512 A047808 A007980
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KEYWORD
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nonn,easy
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AUTHOR
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Leonard Smiley (smiley(AT)math.uaa.alaska.edu), Jun 02 2000
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EXTENSIONS
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More terms from Asher Natan Auel (auela(AT)reed.edu)
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