id:A050442 - OEIS Search Results

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Octahedral torus number: a(n)=n^2+2*sum(k^2,k=1..n-1)-2*([(n+1)/2]^2+2*sum(k^2,k=1..[(n+1)/2]-1))+(1-(-1)^n)/2.

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0, 4, 8, 32, 48, 108, 144, 256, 320, 500, 600, 864, 1008, 1372, 1568, 2048, 2304, 2916, 3240, 4000, 4400, 5324, 5808, 6912, 7488, 8788, 9464, 10976, 11760, 13500, 14400, 16384, 17408, 19652, 20808, 23328, 24624, 27436, 28880, 32000, 33600, 37044 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`a(n)=A005900(n)-2*A005900([(n+1)/2])+(1-(-1)^n)/2`
	FORMULA	`a(n)=(2n^3+n)/3-2/3(2*[(n+1)/2]^3+[(n+1)/2])+(1-(-1)^n)/2`
	CROSSREFS	`Cf. A005900.` `Sequence in context: A129195 A124143 A034041 this_sequence A094015 A094867 A149093` `Adjacent sequences: A050439 A050440 A050441 this_sequence A050443 A050444 A050445`
	KEYWORD	`easy,nice,nonn`
	AUTHOR	`Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 23 1999`

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Last modified December 13 23:45 EST 2009. Contains 170824 sequences.

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