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Search: id:A131908
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| A131908 |
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Smallest positive integer k with the same sum of cubes of divisors as the n-th integer for which such a k exists. |
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+0
7
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| 184926, 291741, 583482, 1166964, 1458705, 1880574, 2042187, 2333928, 2404038, 2917410, 3209151, 3513594, 3792633, 4084374, 4253298, 4667856, 4959597, 5543079, 5362854, 5834820, 5732706, 6418302, 6710043, 7293525, 7585266
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Max Alekseyev, List of first 224 pairs A131907(n), A131908(n)
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FORMULA
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a(n)=min(k>0, k has the same sum of cubes of divisors as A131907(n))
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EXAMPLE
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a(1)=184926 because A131907(1)=194315 with the sum of cubes of its divsors being 7401260364550416. This is the same as the sum of cubes of divisors of 184926 and there is no positive integer less than 184926 with this cubesum of its divisors
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MATHEMATICA
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Last@Transpose[Reap[For[n = 1, n <= 5*10^6, n++, (If[Head[ #1] === tmp, #1 = n, Sow[{n, #1}]] & )[ tmp[DivisorSigma[3, n]]]]][[2, 1]]]
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CROSSREFS
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Cf. A069822, A131902-A131907.
Sequence in context: A024754 A024762 A140933 this_sequence A117225 A032748 A092013
Adjacent sequences: A131905 A131906 A131907 this_sequence A131909 A131910 A131911
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KEYWORD
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nonn
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AUTHOR
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Peter Pein (petsie(AT)dordos.net), Jul 26 2007, Jul 28 2007
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EXTENSIONS
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More terms from Max Alekseyev (maxale(AT)gmail.com), Jul 28 2007
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