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A132295
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Sum of the first n nonsquare numbers.
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0
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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; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| Let r = floor(sqrt(n)). Then a(n) = n(n+1)/2 - r(r+1)(2r+1)/6.
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EXAMPLE
| Let n=5.
The sum of the nonsquare numbers <= 5 is 2+3+5 = 10, the 5-th entry in the sequence.
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PROG
| (PARI) sumNsq(n)= { for(x=1, n, r=floor(sqrt(x)); sq=r*(r+1)*(2*r+1)/6; sn=x*(x+1)/2; print1(sn-sq", ")) }
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CROSSREFS
| Sequence in context: A034387 A081240 A184443 * A086651 A074495 A081467
Adjacent sequences: A132292 A132293 A132294 * A132296 A132297 A132298
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KEYWORD
| nonn
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AUTHOR
| Cino Hilliard (hillcino368(AT)hotmail.com), Nov 07 2007
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