A263572 - OEIS

A263572

Numbers n that minimize sigma(n) / (n^(1-delta) d(n)) for some delta > 0, where d = divisor count = A000005, sigma = divisor sum = A000203.

1, 2, 6, 12, 60, 120, 360, 2520, 5040, 55440, 720720, 1441440, 4324320, 21621600, 367567200, 6983776800, 13967553600, 321253732800, 2248776129600, 65214507758400, 195643523275200, 6064949221531200, 12129898443062400, 448806242393308800, 18401055938125660800

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

These are the miserable average divisor numbers. Similar to superior highly composite numbers (A002201) or colossally abundant numbers (A004490).

a(2)..a(26) are also the first 25 terms of A002201.

LINKS

William C. Jagy, Table of n, a(n) for n = 1..93

Mathematics Stack Exchange, Bounds on the average of the divisors of natural numbers

CROSSREFS

Cf. A000005, A000203, A002201, A004490.

Sequence in context: A265125 A328549 A002201 * A004490 A224078 A309811

Adjacent sequences: A263569 A263570 A263571 * A263573 A263574 A263575

KEYWORD

nonn

AUTHOR

William C. Jagy, Oct 21 2015

STATUS

approved