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Search: id:A111715
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| A111715 |
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Sum of the squares of the first n square-free numbers. |
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+0
4
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| 0, 1, 5, 14, 39, 75, 124, 224, 345, 514, 710, 935, 1224, 1585, 2026, 2510, 3039, 3715, 4556, 5456, 6417, 7506, 8662, 9887, 11256, 12700, 14221, 15902, 17666, 19515, 21631, 23840, 26441, 29250, 32275, 35524, 38888, 42369, 46090, 49934, 54159
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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a(n) is prime for a(2) = 5, a(23) = 9887, a(26) = 14221, ... a(n) is semiprime for n = 3, 4, 9, 13, 14, 16, 17, 27, 30, 32, 39, 43, 44, 46, 47, ...
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LINKS
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Eric Weisstein's World of Mathematics, Squarefree.
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FORMULA
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a(n) = A005117(1)^2 + ... A005117(n)^2.
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EXAMPLE
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a(10) = 1^2 + 2^2 + 3^2 + 5^2 + 6^2 + 7^2 + 10^2 + 11^2 + 13^2 + 14^2 = 710.
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CROSSREFS
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Cf. A005117.
Sequence in context: A054486 A072130 A045553 this_sequence A024525 A119996 A027089
Adjacent sequences: A111712 A111713 A111714 this_sequence A111716 A111717 A111718
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KEYWORD
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nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 17 2005
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