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A051027
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a(n) = sigma(sigma(n)) = sum of the divisors of the sum of the divisors of n.
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19
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1, 4, 7, 8, 12, 28, 15, 24, 14, 39, 28, 56, 24, 60, 60, 32, 39, 56, 42, 96, 63, 91, 60, 168, 32, 96, 90, 120, 72, 195, 63, 104, 124, 120, 124, 112, 60, 168, 120, 234, 96, 252, 84, 224, 168, 195, 124, 224, 80, 128, 195, 171, 120, 360, 195, 360, 186, 234, 168, 480, 96
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..5000
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MAPLE
| with(numtheory): [seq(sigma(sigma(n)), n=1..100)];
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MATHEMATICA
| lst={}; Do[AppendTo[lst, DivisorSigma[1, DivisorSigma[1, n]]], {n, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 11 2009]
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CROSSREFS
| Cf. A000203.
Sequence in context: A070286 A047536 A093494 * A073435 A086987 A051219
Adjacent sequences: A051024 A051025 A051026 * A051028 A051029 A051030
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KEYWORD
| easy,nice,nonn
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AUTHOR
| Judson D. Neer (judson(AT)poboxes.com)
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