A051540 Least common multiple of {2, 5, 8, 11, 14, ..., 3n+2} (A016789).

2, 10, 40, 440, 3080, 52360, 52360, 1204280, 15655640, 454013560, 1816054240, 1816054240, 34505030560, 1414706252960, 1414706252960, 66491193889120, 332455969445600, 17620166380616800, 17620166380616800

Offset: 0

Author

Asher Auel

Keywords

• easy
• frac
• nonn

Comments

Denominator of H(n,3,2), a generalized harmonic number. See A075135.

Examples

			a(3) = lcm{2, 5, 8, 11} = 440.
		

Links

• Robert Israel, Table of n, a(n) for n = 0..1026 (first 100 terms from Vincenzo Librandi)

Crossrefs

Cf. A016789, A051552. The numerators are in A074597.

Cf. A075135.

Cf. A051536.

Programs

GAP

List([0..20],n->Lcm(List([0..n],k->3*k+2))); # Muniru A Asiru, Apr 14 2018

Magma

k:=56; [Lcm([h: h in [2..j by 3]]): j in [2..k by 3]];  // Bruno Berselli, May 03 2011

Maple

A[0]:= 2:
for n from 1 to 60 do A[n]:= ilcm(A[n-1],3*n+2) od:
seq(A[n],n=0..60); # Robert Israel, Apr 10 2018

Mathematica

Table[ Denominator[ Sum[1/i, {i, 2/3, n}]], {n, 1, 20}]
Table[ Apply[ LCM, Join[{1}, Table[2 + 3i, {i, 0, n}]]], {n, 0, 19}]

PARI

a(n) = lcm(vector(n+1, k, 3*k-1)); \\ Michel Marcus, Apr 10 2018

Extensions

Edited by Robert G. Wilson v, Aug 27 2002

Offset corrected by Robert Israel, Apr 10 2018