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

31, 161159, 2935241, 12393851, 25792148743, 8378273888129

Offset: 1

Author

Farideh Firoozbakht, May 13 2005, May 27 2008

Keywords

• nonn
• base
• fini
• more

Comments

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

The sequence is finite as m > 10^(k-1) grows faster than prime(prime(prime(9^k))) >= prime(prime(prime(d_1*d_2*...*d_k))). - Max Alekseyev, Dec 30 2024

Examples

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

Crossrefs

Cf. A097223, A107120, A107121.

Programs

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}]

Extensions

a(6) from Giovanni Resta, Jun 01 2020