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

Comments

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

Links

Amiram Eldar, Table of n, a(n) for n = 0..13

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. A000203 (sigma), 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

Status

approved