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

1,1

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

Formula

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

Mathematica

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

Crossrefs

Cf. A002110, A001221, A097250.

Sequence in context: A276707 A350561 A083484 * A097250 A188328 A291772

Adjacent sequences: A088857 A088858 A088859 * A088861 A088862 A088863

Keyword

nonn

Author

Lekraj Beedassy, Nov 25 2003

Extensions

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

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

Status

approved