A074906 Aliquot sequence starting at 1521.

1521, 858, 1158, 1170, 2106, 2976, 5088, 8520, 17400, 38400, 88452, 196924, 228004, 255836, 255892, 339948, 708372, 1392748, 1392804, 2631580, 3684548, 3684604, 4502876, 4502932, 4630444, 5343604, 5343660, 13185396, 26489484

Offset: 0

Author

Robert A. Stump (bee_ess107(AT)msn.com), Sep 30 2002

Keywords

• nonn
• fini
• full

Comments

This aliquot sequence starts with the least odd number such that the sequence does not repeat a term after 20 or fewer terms.

Examples

			a(0)= 1521, a(1) = sigma(1521) - 1521 = 858.
		

References

• R. K. Guy, Unsolved Problems in Number Theory, B6.

Links

• T. D. Noe, Table of n, a(n) for n = 0..169
• Christophe CLAVIER, Aliquot Sequences

Crossrefs

Cf. A008888, A008889.

Programs

Mathematica

FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 1521] // Most (* Jean-François Alcover, Mar 28 2020 *)

Formula

a(n+1) = A001065(a(n)). - R. J. Mathar, Oct 11 2017