A078423 Group the natural numbers into clumps with increasing prime numbers of elements, then multiply the members of each clump.

2, 60, 30240, 98017920, 857180548224000, 109720581991308288000, 70265584374661732509573120000, 61765285634580106110458762035200000, 642817384174195049892129048242945261568000000

Offset: 1

Author

Lior Manor, Dec 29 2002

Keywords

• nonn

Examples

			Dividing 1,2,3,4,5,6,7,8,9,10,... into clumps of 2,3,5,.. elements: {1,2}, {3,4,5}, {6,7,8,9,10}, ... and then multiply each clumps to get 2,60,30240,...
		

Crossrefs

Cf. A007504, A034956.

Formula

a(n) = A007504(n)!/A007504(n-1)!. - Andrew Howroyd, Oct 16 2023