A131908 Smallest positive integer k with the same sum of cubes of divisors as the n-th integer for which such a k exists.

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

Offset: 1

Author

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

Keywords

• nonn

Examples

			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
		

Links

• Max Alekseyev, List of first 224 pairs A131907(n), A131908(n)

Crossrefs

Cf. A069822, A131902-A131907.

Programs

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]]]

Formula

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

Extensions

More terms from Max Alekseyev, Jul 28 2007