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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
1, 163800, 1547520, 81254720 (list; graph; refs; listen; history; text; internal format)
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

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Last modified September 24 19:49 EDT 2022. Contains 356949 sequences. (Running on oeis4.)