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Search: id:A057789
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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
1
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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; listen)
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OFFSET
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1,3
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COMMENT
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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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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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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
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Sequence in context: A053892 A013126 A012969 this_sequence A123169 A023863 A024480
Adjacent sequences: A057786 A057787 A057788 this_sequence A057790 A057791 A057792
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Nov 04 2000
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