

A110072


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


1




OFFSET

1,2


COMMENTS

No more terms up to 10^25. It is very probable that there is no greater term.  Robert Gerbicz, May 09 2008


LINKS

Table of n, a(n) for n=1..4.


EXAMPLE

81254720 is in the sequence because 81254720 = sigma(8!!*1!!*2!!*5!!*4!!*7!!*2!!*0!!).


MATHEMATICA

Do[h = IntegerDigits[n]; l = Length[h]; If[n == DivisorSigma[1, Product[h[[k]]!!, {k, l}]], Print[n]], {n, 0, 100000000}]


CROSSREFS

Cf. A000203, A097655, A110070, A110071.
Sequence in context: A204653 A031677 A234989 * A196675 A034603 A234680
Adjacent sequences: A110069 A110070 A110071 * A110073 A110074 A110075


KEYWORD

base,more,nonn


AUTHOR

Farideh Firoozbakht, Jul 22 2005


STATUS

approved



