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Search: id:A051444
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| A051444 |
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Smallest k such that sigma(k) = n, or 0 if there is no such k, where sigma(i) = A000203(i) = sum of divisors of i. |
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12
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| 1, 0, 2, 3, 0, 5, 4, 7, 0, 0, 0, 6, 9, 13, 8, 0, 0, 10, 0, 19, 0, 0, 0, 14, 0, 0, 0, 12, 0, 29, 16, 21, 0, 0, 0, 22, 0, 37, 18, 27, 0, 20, 0, 43, 0, 0, 0, 33, 0, 0, 0, 0, 0, 34, 0, 28, 49, 0, 0, 24, 0, 61, 32, 0, 0, 0, 0, 67, 0, 0, 0, 30, 0, 73, 0, 0, 0, 45, 0, 57, 0, 0, 0, 44, 0, 0, 0, 0, 0
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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R. K. Guy, Unsolved Problems Theory of Numbers, B1.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
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EXAMPLE
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sigma(4)=7, 4 is the smallest, so a(7)=4.
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MATHEMATICA
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Do[ k = 1; While[ DivisorSigma[ 1, k ] != n && k < 10^4, k++ ]; If[ k != 10^4, Print[ k ], Print[ 0 ] ], {n, 1, 100} ]
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CROSSREFS
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Cf. A002192, A000203, A007626.
Sequence in context: A080367 A066913 A090303 this_sequence A057637 A167485 A140508
Adjacent sequences: A051441 A051442 A051443 this_sequence A051445 A051446 A051447
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Jud McCranie (j.mccranie(AT)comcast.net)
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