A099996 a(n) = lcm{1, 2, ..., 2*n}.

1, 2, 12, 60, 840, 2520, 27720, 360360, 720720, 12252240, 232792560, 232792560, 5354228880, 26771144400, 80313433200, 2329089562800, 144403552893600, 144403552893600, 144403552893600, 5342931457063200, 5342931457063200

Offset: 0

Author

N. J. A. Sloane, Nov 20 2004

Keywords

• easy
• nonn

Comments

The prime number theorem implies that a(n) = e^(2n(1+o(1))) as n -> infinity. In other words, log(a(n))/n -> 2 as n -> infinity. (Sondow)

Examples

			The LCM of {1,2,3,4,5,6} is 60 and 6 = 2*3, so a(3) = 60.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..1000
• Jonathan Sondow, Criteria for irrationality of Euler's constant, Proc. Amer. Math. Soc. 131 (2003) 3335-3344.
• Index entries for sequences related to lcm's

Crossrefs

Bisection of A003418.

Cf. A076100, A093880.

Cf. A051173.

Programs

Haskell

a099996 = foldl lcm 1 . enumFromTo 2 . (* 2)
-- Reinhard Zumkeller, Feb 11 2014

Maple

A099996 := proc(n)
        lcm(seq(i,i=1..2*n)) ;
end proc: # R. J. Mathar, Dec 14 2011

PARI

a(n) = lcm(vector(2*n, k, k)); \\ Michel Marcus, Mar 18 2018

Extensions

More terms from Jonathan Sondow, Jan 17 2005