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Search: id:A069250
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| A069250 |
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Sum of the reversals of the proper divisors of n. |
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+0
2
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| 0, 1, 1, 3, 1, 6, 1, 7, 4, 8, 1, 16, 1, 10, 9, 15, 1, 21, 1, 13, 11, 14, 1, 45, 6, 34, 13, 55, 1, 69, 1, 76, 15, 74, 13, 127, 1, 94, 35, 23
(list; graph; listen)
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OFFSET
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1,4
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LINKS
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Pe, J. The Picture-Perfect Numbers
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EXAMPLE
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The proper divisors of 20 are 1,2,4,5,10, which reversed are 1,2,4,5,1, summing to 13. Therefore a(10) = 13.
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MATHEMATICA
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f[n_] := FromDigits[Reverse[IntegerDigits[n]]]; g[n_] := Apply[Plus, Map[f, Drop[Divisors[n], -1]]]; Table[g[i], {i, 1, 40}]
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CROSSREFS
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Cf. A069192.
Sequence in context: A076889 A134689 A117552 this_sequence A001065 A109646 A007650
Adjacent sequences: A069247 A069248 A069249 this_sequence A069251 A069252 A069253
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KEYWORD
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base,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Apr 19 2002
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