

A131908


Smallest positive integer k with the same sum of cubes of divisors as the nth integer for which such a k exists.


9



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
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OFFSET

1,1


LINKS



FORMULA

a(n)=min(k>0, k has the same sum of cubes of divisors as A131907(n))


EXAMPLE

a(1)=184926 because A131907(1)=194315 with the sum of cubes of its divisors 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


MATHEMATICA

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]]]


CROSSREFS



KEYWORD

nonn


AUTHOR

Peter Pein (petsie(AT)dordos.net), Jul 26 2007, Jul 28 2007


EXTENSIONS



STATUS

approved



