id:A014409 - OEIS Search Results

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Number of inequivalent ways a pair of checkers can be placed on an n X n board.

+0
5

0, 2, 8, 21, 49, 93, 171, 278, 446, 660, 970, 1347, 1863, 2471, 3269, 4188, 5356, 6678, 8316, 10145, 12365, 14817, 17743, 20946, 24714, 28808, 33566, 38703, 44611, 50955, 58185, 65912, 74648, 83946, 94384, 105453, 117801, 130853 (list; graph; listen)

	OFFSET	`1,2`
	REFERENCES	`Computed by Fred Hallden.`
	FORMULA	`a(2n) = n/2 (2n^3 + 3n - 1); a(2n + 1) = n/2 (2n^3 + 4n^2 + 7n + 3)`
	CROSSREFS	`Cf. A054252, A019318.` `Adjacent sequences: A014406 A014407 A014408 this_sequence A014410 A014411 A014412` `Sequence in context: A141582 A000160 A034519 this_sequence A109782 A123044 A143229`
	KEYWORD	`nonn,nice,easy`
	AUTHOR	`Borghard, William (bogey(AT)hostare.att.com)`
	EXTENSIONS	`More terms and formula from Hugo van der Sanden (hv(AT)crypt.org)`

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Last modified October 10 20:39 EDT 2008. Contains 144831 sequences.

AT&T Labs Research