A098683 Numbers n such that pi(n) = prime(d_1)*prime(d_2)*...*prime(d_k) where d_1 d_2 ... d_k is the decimal expansion of n.

123, 5224, 11166, 51174, 172451, 546322, 14355351, 23539612, 23539621, 24322837, 122924349, 4575242147, 42256772524, 283186883151, 623286236455, 665318971119, 665318971191, 5257788212426, 27452719198281, 273643846355134, 787812731751347, 787812731751374

Offset

1,1

Comments

a(n) must necessarily be a zeroless number, i.e., the sequence is a subsequence of A052382. - Chai Wah Wu, Mar 04 2019

Links

Table of n, a(n) for n=1..22.

Example

122924349 is in the sequence because pi(122924349) = P(1)*P(2)*P(2)*P(9)*P(2)*P(4)*P(3)*P(4)*P(9) where P(i) is i-th prime.

Mathematica

Do[d=IntegerDigits[n]; k=Length[d]; If[ !MemberQ[d, 0]&&PrimePi[n]==Product[Prime[d[[j]]], {j, k}], Print[n]], {n, 230000000}]

Crossrefs

Cf. A052382, A097227, A098684, A098685, A160040.

Sequence in context: A293309 A297754 A068239 * A324435 A135479 A095761

Adjacent sequences: A098680 A098681 A098682 * A098684 A098685 A098686

Keyword

base,nonn

Author

Farideh Firoozbakht, Sep 24 2004

Extensions

Entries corrected by Robert G. Wilson v, May 04 2009

a(13)-a(17) from Donovan Johnson, Jul 12 2010

a(18) from Giovanni Resta, Apr 01 2017

a(19) from Chai Wah Wu, Mar 05 2019

a(20)-a(22) from Chai Wah Wu, Mar 06 2019

Status

approved