A088860 Twice the primorials (first definition), 2*A002110(n).

4, 12, 60, 420, 4620, 60060, 1021020, 19399380, 446185740, 12939386460, 401120980260, 14841476269620, 608500527054420, 26165522663340060, 1229779565176982820, 65178316954380089460, 3845520700308425278140

Offset: 1

Author

Lekraj Beedassy, Nov 25 2003

Keywords

• nonn

Comments

Also, least number m divisible by 4 such that omega(m)=n, where omega=A001221.

Refers to the least number which is the leg of exactly 2^(n-1) primitive Pythagorean triangles.

For n >= 1, a(n) = A097250(n). - G. C. Greubel, Apr 23 2017

Links

• G. C. Greubel, Table of n, a(n) for n = 1..345

Crossrefs

Cf. A002110, A001221, A097250.

Programs

Mathematica

2*FoldList[Times, 1, Prime[Range[50]]] (* G. C. Greubel, Apr 23 2017 *)

Formula

a(n) = 2*#p(n) = 2*A002110(n).

Extensions

Corrected by G. C. Greubel, Apr 23 2017.

Edited by N. J. A. Sloane, Apr 23 2017