A092980 Partition the sequence of natural numbers into groups so that each group product is just >=n! until the group contains only one number which is >= n!; a(n) = the number of such groups.

1, 2, 3, 12, 58, 355, 2507, 20123, 181332, 1814067, 19957313, 239497077, 3113497076, 43589095986, 653836992433, 10461394179218, 177843710898562, 3201186839512209, 60822550146244234, 1216451003828243036

Offset

1,2

Comments

The largest member of the second group is given by A092979(n).

Links

Table of n, a(n) for n=1..20.

Example

For n = 3 the groups are (1,2,3), (4,5), (6) so a(3)= 3.
For n = 4 the groups are (1,2,3,4),(5,6),(7,8),(9,10),(11,12),(13,14),(15,16),(17,18),(19,20),(21,22),(23,24),(25), so a(4) = 12.
For n = 7 the groups are (1,2,3,4,5,6,7), (8,9,10,11), (12,13,14,15),(16,17,18,19),(20,21,22),(23,24,25),(26,27,28),... so a(7)= 2507.

Crossrefs

Cf. A092979.

The largest member of the second group is given by A092979(n).

Sequence in context: A025231 A366454 A094532 * A191464 A052183 A123899

Adjacent sequences: A092977 A092978 A092979 * A092981 A092982 A092983

Keyword

nonn

Author

Bobby L. Wilson (bwilson4(AT)radar.gsw.edu), following a suggestion of Amarnath Murthy, Jun 05 2004

Extensions

More terms from John W. Layman, Nov 18 2004

Further terms from William Rex Marshall, Jun 22 2005

Status

approved