A269542 Aliquot sequence starting at 702.

702, 978, 990, 1818, 2160, 5280, 12864, 21680, 28912, 31848, 47832, 71808, 148512, 359520, 946848, 1895712, 4539360, 12180336, 23781648, 44267568, 76111632, 139130668, 104348008, 92030552, 80526748, 62286692, 55099864, 51042536, 47249404, 35492780, 39042100

Offset: 0

Author

Daniel Mondot, Feb 29 2016

Keywords

• nonn
• fini
• full

Comments

This sequence is one of the first ones that contains numbers that exceed 2^64 and yet is known to terminate in a small prime followed by 1 and 0.

Note how all the numbers in the sequence are even, except the last 6 (not counting 0).

References

• R. K. Guy, Unsolved Problems in Number Theory, B6.
• Enoch Haga, Exploring Prime Numbers on Your PC, 2nd ed., 1998, pages 83-84 and Table 8, page 46. ISBN 1-885794-16-9.

Links

• Daniel Mondot, Table of n, a(n) for n = 0..301

Crossrefs

Cf. A001065, A008888.

Programs

Mathematica

NestWhileList[DivisorSigma[1,#]-#&,702,#>0&] (* Paolo Xausa, Oct 16 2023 *)

PARI

lista() = {print1(a=702, ", "); until (!a, a = sigma(a) - a; print1(a, ", "););} \\ Michel Marcus, Feb 29 2016

Formula

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