A062723 Least common multiple (LCM) of the first n+1 terms of A000792.

1, 1, 2, 6, 12, 12, 36, 36, 36, 108, 108, 108, 324, 324, 324, 972, 972, 972, 2916, 2916, 2916, 8748, 8748, 8748, 26244, 26244, 26244, 78732, 78732, 78732, 236196, 236196, 236196, 708588, 708588, 708588, 2125764, 2125764, 2125764, 6377292, 6377292

Offset: 0

Author

Felix Goldberg (felixg(AT)tx.technion.ac.il), Jul 15 2001

Keywords

• easy
• nonn

Comments

Apparently this sequence (when taken without repeats) is a subsequence of A000792, cf. A202337.

Examples

			a(4)=12 because a(4) is the LCM of 1,1,2,3,4 - which is clearly 12.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 0..400
• Index entries for sequences related to lcm's
• Index entries for linear recurrences with constant coefficients, signature (0, 0, 3).

Crossrefs

Cf. A000244, A000792.

Programs

Haskell

a062723 n = a062723_list !! n
a062723_list = scanl1 lcm a000792_list
-- Reinhard Zumkeller, Dec 17 2011

Mathematica

Module[{nn=50,trms},trms=CoefficientList[Series[(1+x+2x^2+x^4)/(1-3x^3),{x,0,nn}],x];Table[LCM@@Take[trms,n],{n,nn}]] (* or *) LinearRecurrence[{0,0,3},{1,1,2,6,12,12,36},50] (* Harvey P. Dale, Oct 04 2024 *)

PARI

a(n)=if(n<0,0,if(n<4,n!,4*3^(n\3)))

Formula

a(n) = 4*3^floor(n/3), n >= 3. - Vladeta Jovovic, Jul 18 2001

G.f.: (1+x+2*x^2+3*x^3+9*x^4+6*x^5+18*x^6)/(1-3*x^3).

Extensions

Formula and correction from Vladeta Jovovic, Jul 18 2001

More terms from Jason Earls, Jul 21 2001