login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A051426 Least common multiple of {2, 4, 6, ..., 2n}. 4
2, 4, 12, 24, 120, 120, 840, 1680, 5040, 5040, 55440, 55440, 720720, 720720, 720720, 1441440, 24504480, 24504480, 465585120, 465585120, 465585120, 465585120, 10708457760, 10708457760, 53542288800, 53542288800, 160626866400, 160626866400, 4658179125600 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Gcd(A025547(n), a(n)) = A025547(floor((n+1)/2)). - Reinhard Zumkeller, Apr 25 2011
REFERENCES
A. Murthy, Some new Smarandache sequences, functions and partitions, Smarandache Notions Journal Vol. 11 N. 1-2-3 Spring 2000 (but beware errors).
LINKS
FORMULA
a(n) = a(n-1)*lcm(a(n-1),2n) = a(n-1)* A014963(n). - Zak Seidov, Aug 01 2009
EXAMPLE
a(3) = lcm{2,4,6} = 12;
a(7) = lcm{2,4,6,8,10,12,14} = 840.
MATHEMATICA
SZ={2}; n=2; L=2; Do[L=LCM[L, 2n]; AppendTo[SZ, L]; n++, {99}]; SZ (* Zak Seidov, Aug 01 2009 *)
Table[LCM@@Range[2, 2n, 2], {n, 30}] (* Harvey P. Dale, Oct 09 2011 *)
PROG
(Haskell)
a051426 n = foldl lcm 1 [2, 4..2*n] -- Reinhard Zumkeller, Apr 25 2011
(PARI) a(n)=2*lcm([1..n]) \\ Charles R Greathouse IV, Oct 28 2016
CROSSREFS
Sequence in context: A096421 A066843 A051905 * A048148 A080375 A136253
KEYWORD
easy,nice,nonn
AUTHOR
EXTENSIONS
a(6), a(7) and a(8) corrected by T. D. Noe, Feb 08 2008
Corrected the example, which did not reflect the sequence values provided. - Michael Davies (mykdavies+oeis(AT)gmail.com), Oct 10 2008
Edited by N. J. A. Sloane, Jul 31 2009 at the suggestion of R. J. Mathar
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 04:13 EDT 2024. Contains 371235 sequences. (Running on oeis4.)