A134716 a(n) = least number m such that sigma(m)/m > n, where sigma(m) = sum of divisors of m.

1, 2, 12, 180, 27720, 122522400, 130429015516800, 1970992304700453905270400, 1897544233056092162003806758651798777216000, 4368924363354820808981210203132513655327781713900627249499856876120704000

Offset

0,2

Links

Table of n, a(n) for n=0..9.

Example

Values written as products of primorials:
n a(n)
0 1
1 2
2 2*3#
3 3#*5# (= 180)
4 2*3#*11#
5 8*5#*17#
6 16*3#*7#*29#
7 8*3#*3#*7#*53#
8 32*3#*3#*5#*11#*89#
9 32*3#*3#*7#*17#*157#
10 16*3#*3#*5#*7#*23#*271#
11 16*3#*3#*5#*7#*29#*487#
12 16*3#*3#*5#*7#*13#*31#*857#

Crossrefs

Cf. A023199 (least k with sigma(k) >= nk)

Sequence in context: A156516 A228593 A067962 * A243807 A006023 A039748

Adjacent sequences: A134713 A134714 A134715 * A134717 A134718 A134719

Keyword

nonn

Author

Pierre CAMI, Jan 27 2008, corrected Feb 26 2008 with the help of Emeric Deutsch

Extensions

More terms can be obtained by expanding the expressions in the example lines. - N. J. A. Sloane, Feb 26 2008

Status

approved