OFFSET
1,1
LINKS
Daniel Mondot, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Multiplicative Persistence
EXAMPLE
277 -> [ 98 ][ 72 ][ 14 ][ 4 ] -> one digit in four steps.
MATHEMATICA
pmp4Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&, n, #>9&]]==5; Select[Prime[Range[500]], pmp4Q] (* Harvey P. Dale, Oct 10 2016 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Sep 15 1998
STATUS
approved