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A098499
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Number of squares on infinite half chessboard at <=n knight moves from a fixed point on the diagonal.
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4
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1, 5, 23, 57, 109, 169, 246, 334, 439, 555, 688, 832, 993, 1165, 1354, 1554, 1771, 1999, 2244, 2500, 2773, 3057, 3358, 3670, 3999, 4339, 4696, 5064, 5449, 5845, 6258, 6682, 7123, 7575, 8044, 8524, 9021, 9529, 10054, 10590, 11143, 11707
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| (1/4) [28n^2 - 6n + 9 + 3(-1)^n], for n>3.
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EXAMPLE
| 5 squares are reachable after 1 move, from these you can reach 18 new squares more, so a(1)=5, a(2)=23.
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CROSSREFS
| Equals A098498(n) - A052938(n-4), n>3.
See A018836 (unbounded), A098498 (halfplane), A098500 (quadrant), A098501 (octant).
Sequence in context: A053664 A186030 A092544 * A075565 A075707 A126420
Adjacent sequences: A098496 A098497 A098498 * A098500 A098501 A098502
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KEYWORD
| nonn
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AUTHOR
| Ralf Stephan (ralf(AT)ark.in-berlin.de), Sep 15 2004
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