

A139182


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


1



50, 51, 125, 15405, 26205, 226700, 226701, 226710, 226711, 513090, 513091, 1351832, 8210065
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OFFSET

1,1


COMMENTS

Numbers m with a product of the doublefactorials of the digits equal to A000720(m).
If { m is in the sequence, 10 divides m and m+1 is composite } then m+1 is in the sequence. [Clarified by N. J. A. Sloane, Feb 06 2022]


LINKS



EXAMPLE

pi(8210065)=8!!*2!!*1!!*0!!*0!!*6!!*5!!.


MATHEMATICA

Select[Range[83*10^5], Times@@(IntegerDigits[#]!!)==PrimePi[#]&] (* Harvey P. Dale, Apr 12 2024 *)


CROSSREFS



KEYWORD

base,nonn,less,more


AUTHOR



STATUS

approved



