A080509 Last term in n-th row of A080508.

1, 4, 4, 216, 324, 6075000, 30375000, 750453558750000, 19699405917187500, 459652804734375000, 9652708899421875000, 578346405423301688948883281250000, 111331683043985575122660031640625000, 77892265302487151682927242578030755976166730468750000

Offset

1,2

Links

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..54

Formula

For n!=2, a(n) = (A034386(n - 1))^n / (n - 1)!. - Jeppe Stig Nielsen, Nov 04 2018

Example

For n=5, first four terms of row are 1, 2, 3, 4, with product 24 = 2^3*3^1. So last term is 2^(5-3)*3^(5-1) = 2^2*3^4 = 324.

Mathematica

MapAt[4 # &, Array[Apply[Times, Prime@ Range@ PrimePi[# - 1]]^#/(# - 1)! &, 14], 2] (* Michael De Vlieger, Nov 05 2018 *)

Prog

(PARI) a(n) = {if (n == 1, return (1)); if (n == 2, return (2^2)); f  = factor((n-1)!); prod(i = 1, #f~, f[i, 1]^(n - f[i, 2])); } \\ Michel Marcus, Aug 30 2013
(PARI) a(n) = if(n==2, 4, prod(i=1, primepi(n-1), prime(i))^n/(n-1)!) \\ Jeppe Stig Nielsen, Nov 04 2018

Crossrefs

Cf. A080508.

Sequence in context: A097572 A160365 A264517 * A063439 A218050 A107052

Adjacent sequences: A080506 A080507 A080508 * A080510 A080511 A080512

Keyword

nonn

Author

Amarnath Murthy, Mar 20 2003

Extensions

More terms from Michel Marcus, Aug 30 2013

Status

approved