A073329 a(n) is the n-th number to have n distinct prime factors.

2, 10, 60, 420, 4290, 53130, 903210, 17687670, 406816410, 11125544430, 338431883790, 11833068917670, 457077357006270, 20384767656323070, 955041577211912190, 49230430891074322890, 2740956243836856315270, 168909608387276001835590, 11054926927790884163355330

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..350 (terms <= 10^1000)

Formula

A001221(a(n)) = n <= A001222(a(n)). - Alois P. Heinz, Jan 09 2021

Example

a(1) = 2 because 2 is the first number to have one prime factor.
a(2) = 10 because 10 is the second number to have two prime factors; 6 is the first.
a(3) = 60 = 2*2*3*5 because 60 is the third number to have three prime factors (2,3,5); 30 is the first and 42 is the second.

Crossrefs

a(n) is last term in n-th row of A048692.

Cf. A001221, A001222, A340467.

Sequence in context: A082042 A260657 A079856 * A290446 A350225 A277472

Adjacent sequences: A073326 A073327 A073328 * A073330 A073331 A073332

Keyword

nonn

Author

Robert G. Wilson v, Aug 22 2002

Extensions

Edited by Dean Hickerson, Nov 03 2002

More terms from Sascha Kurz, Jan 03 2003

Corrected from a(9) onwards by T. D. Noe, Dec 01 2004

More terms from David A. Corneth, Jan 09 2021

Status

approved