A107122 Numbers n such that n=prime(prime(prime(d_1*d_2*...*d_k))) where d_1 d_2 ... d_k is the decimal expansion of n.

31, 161159, 2935241, 12393851, 25792148743, 8378273888129

Offset

1,1

Comments

a(6) > 111*10^9.

a(7) > 7*10^14, if it exists. - Giovanni Resta, Jun 01 2020

Links

Table of n, a(n) for n=1..6.

Example

12393851 is in the sequence because 12393851 = prime(prime(prime(1*2*3*9*3*8*5*1))).

Mathematica

Do[h= IntegerDigits[Prime[m]]; l = Length[h]; If[Min[h] > 0 && m == Prime[Prime[Prime[Product[h[[k]], {k, l}]]], Print[Prime[m]]]], {m, 10000000}]

Crossrefs

Cf. A097223, A107120, A107121.

Sequence in context: A117579 A249584 A351135 * A059113 A057839 A123524

Adjacent sequences: A107119 A107120 A107121 * A107123 A107124 A107125

Keyword

nonn,base,more

Author

Farideh Firoozbakht, May 13 2005, May 27 2008

Extensions

a(6) from Giovanni Resta, Jun 01 2020

Status

approved