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A099946 a(n) = lcm{1, 2, ..., n}/(n*(n-1)), n >= 2. 2
1, 1, 1, 3, 2, 10, 15, 35, 28, 252, 210, 2310, 1980, 1716, 3003, 45045, 40040, 680680, 612612, 554268, 503880, 10581480, 9699690, 44618574, 41186376, 114406600, 106234700, 2868336900, 2677114440, 77636318760, 145568097675, 136745788725 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

LINKS

Luke March and Alois P. Heinz, Table of n, a(n) for n = 2..1000 (first 99 terms from Luke March)

FORMULA

a(n) = A003418(n)/(n*(n-1)) = A003418(n)/A002378(n-1), n >= 2.

MAPLE

a:= n-> ilcm(seq(k, k=1..n))/n/(n-1): seq(a(n), n=2..37); # Emeric Deutsch, Jun 13 2005

MATHEMATICA

Table[LCM@@Range[n]/(n(n-1)), {n, 2, 40}] (* Harvey P. Dale, Jan 14 2011 *)

PROG

(Python)

from fractions import gcd

def lcm(a, b): return (a*b)/gcd(a, b)

def f(lim):

....l=1

....for x in range(2, lim+1):

........l=lcm(x, l)

........print x, l/(x*(x-1))

f(100) # Luke March, Jul 23 2014

(PARI) a(n) = lcm(vector(n, i, i))/(n*(n-1)); \\ Michel Marcus, Jul 25 2014

CROSSREFS

Cf. A002378, A002944, A003418, A025558.

Sequence in context: A327809 A075856 A025520 * A011953 A038519 A192617

Adjacent sequences:  A099943 A099944 A099945 * A099947 A099948 A099949

KEYWORD

nonn,easy,changed

AUTHOR

N. J. A. Sloane, Nov 12 2004

EXTENSIONS

More terms from Emeric Deutsch, Jun 13 2005

STATUS

approved

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Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)