A114575 Number of distinct prime factors of floor(e^n).

1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 3, 2, 4, 2, 4, 4, 1, 5, 2, 3, 2, 4, 2, 3, 3, 3, 4, 3, 3, 2, 5, 5, 3, 7, 4, 3, 3, 4, 5, 2, 5, 4, 3, 6, 5, 3, 4, 4, 1, 4, 5, 5, 6, 4, 5, 6, 3, 4, 2, 4, 5, 7, 9, 3, 6, 7, 8, 5, 3, 5, 7, 5, 5, 7, 3, 5, 6, 6, 6

Offset

0,3

Links

Table of n, a(n) for n=0..79.

Example

floor(e^3) = floor(20.08553) = 20. 20 has two distinct prime factors (2 and 5), therefore a(3) = 2.

Mathematica

Table[Length[FactorInteger[Floor[E^n]]], {n, 1, 80}]
PrimeNu[Floor[E^Range[80]]] (* Harvey P. Dale, Jul 21 2013 *)

Crossrefs

Cf. A001113 [decimal expansion of e].

Sequence in context: A025809 A204591 A279220 * A131849 A362344 A244479

Adjacent sequences: A114572 A114573 A114574 * A114576 A114577 A114578

Keyword

nonn

Author

Stefan Steinerberger, Feb 17 2006

Status

approved