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Search: id:A053818
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| A053818 |
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Sum_{k=1..n, gcd(n,k) = 1} k^2. |
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+0
3
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| 1, 1, 5, 10, 30, 26, 91, 84, 159, 140, 385, 196, 650, 406, 620, 680, 1496, 654, 2109, 1080, 1806, 1650, 3795, 1544, 4150, 2756, 4365, 3164, 7714, 2360, 9455, 5456, 7370, 6256, 9940, 5196, 16206, 8778, 12324, 8560, 22140, 6972, 25585
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OFFSET
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1,3
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COMMENT
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Equals row sums of triangle A143612 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 27 2008]
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REFERENCES
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T. M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1976, page 48, problem 15, the function phi_2(n).
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 199, #2.
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FORMULA
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If n = p_1^e_1 * ... *p_r^e_r then a(n) = n^2*phi(n)/3 + (-1)^r*p_1*..._p_r*phi(n)/6.
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CROSSREFS
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Cf. A023896, A053819, A053820.
Sequence in context: A105505 A005514 A069921 this_sequence A133629 A048010 A002571
A143612 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 27 2008]
Adjacent sequences: A053815 A053816 A053817 this_sequence A053819 A053820 A053821
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KEYWORD
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nonn,new
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AUTHOR
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njas, Apr 07 2000
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