A093453 1/1, 2*3/lcm(2,3), 4*5*6/lcm(4,5,6), 7*8*9*10/lcm(7,8,9,10), ...

1, 1, 2, 2, 6, 24, 48, 720, 720, 1440, 241920, 120960, 3628800, 14515200, 87091200, 958003200, 261273600, 2615348736000, 804722688000, 125536739328000, 2414168064000, 753220435968000, 256094948229120000, 22596613079040000, 102181884343418880000

Offset

1,3

Links

Table of n, a(n) for n=1..25.

Formula

a(n) = (Product_{j=n*(n-1)/2+1..n*(n+1)/2} j) / lcm(n*(n-1)/2+1, n*(n-1)/2+2, ..., n*(n+1)/2). - Jon E. Schoenfield, Mar 17 2018

a(n) = A057003(n)/A061431(n). - Michel Marcus, Apr 12 2018

Example

a(5) = 6 = (11*12*13*14*15)/lcm(11,12,13,14,15) = 360360/60060.

Maple

a:=n->product(j, j=n*(n-1)/2+1..n*(n+1)/2)/lcm(seq(j, j=n*(n-1)/2+1..n*(n+1)/2)): seq(a(n), n=1..27); # Emeric Deutsch, Aug 07 2005

Crossrefs

Cf. A000217, A057003, A061431.

Sequence in context: A076741 A320603 A276409 * A301381 A342282 A253093

Adjacent sequences: A093450 A093451 A093452 * A093454 A093455 A093456

Keyword

nonn

Author

Amarnath Murthy, Apr 03 2004

Extensions

More terms from Emeric Deutsch, Aug 07 2005

Status

approved