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A062723
Least common multiple (LCM) of the first n+1 terms of A000792.
3
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
0,3
COMMENTS
Apparently this sequence (when taken without repeats) is a subsequence of A000792, cf. A202337.
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).
EXAMPLE
a(4)=12 because a(4) is the LCM of 1,1,2,3,4 - which is clearly 12.
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 *)
PROG
(PARI) a(n)=if(n<0, 0, if(n<4, n!, 4*3^(n\3)))
(Haskell)
a062723 n = a062723_list !! n
a062723_list = scanl1 lcm a000792_list
-- Reinhard Zumkeller, Dec 17 2011
CROSSREFS
Sequence in context: A096075 A278256 A066791 * A152667 A145892 A216429
KEYWORD
easy,nonn
AUTHOR
Felix Goldberg (felixg(AT)tx.technion.ac.il), Jul 15 2001
EXTENSIONS
Formula and correction from Vladeta Jovovic, Jul 18 2001
More terms from Jason Earls, Jul 21 2001
STATUS
approved