cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-1 of 1 results.

A181312 Highly abundant numbers k whose largest prime factor is greater than log(k).

Original entry on oeis.org

1, 2, 3, 4, 6, 10, 12, 18, 20, 30, 42, 60, 84, 90, 120, 168, 210, 336, 420, 504, 630, 660, 840, 1008, 1560, 1980, 2340, 3120, 3960, 4620, 4680, 6120, 6240, 7920, 9240, 10920, 11880, 12240, 13860, 16380, 18480, 19800, 21840, 23760, 27720, 32760, 36960
Offset: 1

Views

Author

T. D. Noe, Oct 13 2010

Keywords

Comments

Every highly abundant number (A002093) is either in this sequence or A181311. Although it appears that dividing any term by its largest prime factor produces another highly abundant number, this conjecture fails for 2942007868800, the 527th term.

Links

Crossrefs

Cf. A002093, A181311.

Programs

  • Mathematica
    seq = {}; sm = 0; Do[s = DivisorSigma[1, n]; If[s > sm, sm = s; If[FactorInteger[n][[-1, 1]] > Log[n], AppendTo[seq, n]]], {n, 1, 37000}]; seq (* Amiram Eldar, Jan 14 2022 *)
Showing 1-1 of 1 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.