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A057789
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Sum_{k = 1..n, gcd(k,n)=1} k*(n-k).
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0
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0, 1, 4, 6, 20, 10, 56, 44, 84, 60, 220, 92, 364, 182, 280, 344, 816, 318, 1140, 520, 840, 770, 2024, 760, 2100, 1300, 2196, 1540, 4060, 1240, 4960, 2736, 3520, 2992, 4760, 2580, 8436, 4218, 5928, 4240, 11480, 3612, 13244, 6380, 8040, 7590, 17296, 6128
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Equal to convolution sum over positive integers, k, where k<=n and GCD(k,n)=1, except in first term, where the convolution sum is 1 instead of 0.
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EXAMPLE
| Since 1, 3, 5 and 7 are relatively prime to 8 and are <= 8, a(8) = 1*(8-1) +3*(8-3) +5*(8-5) +7*(8-7) = 44.
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CROSSREFS
| Sequence in context: A053892 A013126 A012969 * A174936 A123169 A205955
Adjacent sequences: A057786 A057787 A057788 * A057790 A057791 A057792
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Nov 04 2000
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