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A068550 a(n) = lcm{1, ..., 2n} / binomial(2n, n). 4
1, 1, 2, 3, 12, 10, 30, 105, 56, 252, 1260, 330, 1980, 2574, 2002, 15015, 240240, 61880, 15912, 151164, 38760, 406980, 4476780, 1144066, 13728792, 24515700, 6249100, 84362850, 21474180, 5462730, 81940950, 1270084725, 645122400 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Known to be always an integer.

LINKS

Table of n, a(n) for n=0..32.

Hojoo Lee, Re: LCM [1,2,..,N] > 2^{N-1}, NMBRTHRY Mailing List, Feb 18 2002.

FORMULA

a(n) = A099996(n) / A000984(n) = A003418(2*n) / A001405(2*n) = A180000(2*n) = A263673(2*n).

a(n) = n * A068553(n) = n * A048619(2*n-1).

CROSSREFS

Bisection of A180000 and A263673.

Sequence in context: A027611 A303221 A168059 * A093432 A212303 A100561

Adjacent sequences:  A068547 A068548 A068549 * A068551 A068552 A068553

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Mar 23 2002

EXTENSIONS

a(0)=1 prepended by Max Alekseyev, Oct 23 2015

STATUS

approved

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Last modified November 17 16:08 EST 2019. Contains 329241 sequences. (Running on oeis4.)