A097655 Numbers n such that n = d_1!!*d_2!!*...*d_k!! where d_1 d_2 ... d_k is the decimal expansion of n.

1, 2, 3, 15, 18432, 75600, 276531978240000, 4810168001497883738112000, 215788176336727572480000000, 2178419737991700039289327133392896000000000000

Offset: 1

Author

Farideh Firoozbakht, Sep 10 2004

Keywords

• base
• nonn

Comments

All terms are of the form 2^i*3^j*5^k*7^l.

Examples

			18432 is in the sequence because 18432 = 1!!*8!!*4!!*3!!*2!!.
		

Crossrefs

Cf. A097653, A097654, A097643, A102279.

Programs

Mathematica

Do[h=IntegerDigits[n];l=Length[h];If[n==Product[h[[k]]!!, {k, l}], Print[n]], {n, 2000000000}]

Extensions

More terms from Farideh Firoozbakht, Jan 08 2005