A008339 a(1)=1; for n >= 1, a(n+1) = lcm(a(n),n) / gcd(a(n),n).

1, 1, 2, 6, 6, 30, 5, 35, 280, 2520, 252, 2772, 231, 3003, 858, 1430, 5720, 97240, 437580, 8314020, 415701, 969969, 176358, 4056234, 2704156, 67603900, 2600150, 70204050, 10029150, 290845350, 9694845, 300540195, 9617286240, 35263382880, 1037158320

Offset

1,3

Comments

a(n+1) = Product(A098666(n,k): 1<=k<=n), row-products of triangle A098666. - Reinhard Zumkeller, Sep 20 2004

a(n+1) is divisible by all primes in (n/2, n]; thus lim_{n->infinity} a(n) = infinity. - Franklin T. Adams-Watters, Dec 13 2006

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Formula

a(1) = 1, a(n) = a(n-1)*r/s where y is the largest divisor of a(n-1) with r*s = n. - Amarnath Murthy, Jul 01 2003

a(1) = 1, a(n+1) = a(n)*n/gcd(a(n),n)^2. - Franklin T. Adams-Watters, Dec 13 2006

Maple

A008339 := proc(n) option remember; if n = 1 then 1 else lcm(A008339(n-1), n-1)/gcd(A008339(n-1), n-1); fi; end;

Mathematica

FoldList[ LCM[ #1, #2 ]/GCD[ #1, #2 ]&, 1, Range[ 30 ] ] (* Olivier Gérard, Aug 15 1997 *)

Crossrefs

Cf. A249831.

Sequence in context: A072983 A055204 A212397 * A077139 A068629 A144361

Adjacent sequences: A008336 A008337 A008338 * A008340 A008341 A008342

Keyword

nonn

Author

N. J. A. Sloane.

Status

approved