login
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.
1
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
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
KEYWORD
nonn,base,more
AUTHOR
Farideh Firoozbakht, May 13 2005, May 27 2008
EXTENSIONS
a(6) from Giovanni Resta, Jun 01 2020
STATUS
approved