id:A123596 - OEIS Search Results

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Squares alternating with triangular numbers.

+0
2

0, 0, 1, 1, 4, 3, 9, 6, 16, 10, 25, 15, 36, 21, 49, 28, 64, 36, 81, 45, 100, 55, 121, 66, 144, 78, 169, 91, 196, 105, 225, 120, 256, 136, 289, 153, 324, 171, 361, 190, 400, 210, 441, 231, 484, 253, 529, 276, 576, 300, 625, 325, 676, 351, 729, 378, 784, 406, 841, 435 (list; graph; listen)

	OFFSET	`0,5`
	FORMULA	`a(2n)=n^2, a(2n+1)=(n^2+n)/2.`
	PROGRAM	`(PARI) {a(n) = if(n%2, (n^2-1)/8, n^2/4)} /* Michael Somos Nov 18 2006 */`
	CROSSREFS	`Cf. A002620, A124093.` `Sequence in context: A103825 A073238 A010655 this_sequence A094885 A094728 A131805` `Adjacent sequences: A123593 A123594 A123595 this_sequence A123597 A123598 A123599`
	KEYWORD	`nonn`
	AUTHOR	`Peter Hansen (babyskbaby(AT)web.de), Nov 14 2006`
	EXTENSIONS	`Edited by Michael Somos and several other correspondents, Nov 14 2005`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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