login
a(n) = lcm{1, 2, ..., 2*n}.
10

%I #31 May 06 2023 04:22:59

%S 1,2,12,60,840,2520,27720,360360,720720,12252240,232792560,232792560,

%T 5354228880,26771144400,80313433200,2329089562800,144403552893600,

%U 144403552893600,144403552893600,5342931457063200,5342931457063200

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

%C 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)

%H Reinhard Zumkeller, <a href="/A099996/b099996.txt">Table of n, a(n) for n = 0..1000</a>

%H Jonathan Sondow, <a href="https://doi.org/10.1090/S0002-9939-03-07081-3">Criteria for irrationality of Euler's constant</a>, Proc. Amer. Math. Soc. 131 (2003) 3335-3344.

%H <a href="/index/Lc#lcm">Index entries for sequences related to lcm's</a>

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

%p A099996 := proc(n)

%p lcm(seq(i,i=1..2*n)) ;

%p end proc: # _R. J. Mathar_, Dec 14 2011

%o (Haskell)

%o a099996 = foldl lcm 1 . enumFromTo 2 . (* 2)

%o -- _Reinhard Zumkeller_, Feb 11 2014

%o (PARI) a(n) = lcm(vector(2*n, k, k)); \\ _Michel Marcus_, Mar 18 2018

%Y Bisection of A003418.

%Y Cf. A076100, A093880.

%Y Cf. A051173.

%K easy,nonn

%O 0,2

%A _N. J. A. Sloane_, Nov 20 2004

%E More terms from _Jonathan Sondow_, Jan 17 2005