id:A132295 - OEIS Search Results

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Sum of the first n nonsquare numbers.

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0, 2, 5, 5, 10, 16, 23, 31, 31, 41, 52, 64, 77, 91, 106, 106, 123, 141, 160, 180, 201, 223, 246, 270, 270, 296, 323, 351, 380, 410, 441, 473, 506, 540, 575, 575, 612, 650, 689, 729, 770, 812, 855, 899, 944, 990, 1037, 1085, 1085, 1135, 1186, 1238, 1291, 1345 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`Let r = floor(sqrt(n)). Then a(n) = n(n+1)/2 - r(r+1)(2r+1)/6.`
	EXAMPLE	`Let n=5.` `The sum of the nonsquare numbers <= 5 is 2+3+5 = 10, the 5-th entry in the sequence.`
	PROGRAM	`(PARI) sumNsq(n)= { for(x=1, n, r=floor(sqrt(x)); sq=r(r+1)(2r+1)/6; sn=x(x+1)/2; print1(sn-sq", ")) }`
	CROSSREFS	`Sequence in context: A059797 A034387 A081240 this_sequence A086651 A074495 A081467` `Adjacent sequences: A132292 A132293 A132294 this_sequence A132296 A132297 A132298`
	KEYWORD	`nonn`
	AUTHOR	`Cino Hilliard (hillcino368(AT)hotmail.com), Nov 07 2007`

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

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