OFFSET
1,1
COMMENTS
Question: do only a finite number of terms end in a digit other than 1?
Question: is the sequence infinite?
EXAMPLE
911 is not a(3) because 911 is prime.
PROG
(PARI) lista(nn) = {vi = [1, 3, 7, 9]; a = 9; print1(a, ", "); for (n=1, nn, ok = 0; for (i=1, #vi, if (!isprime(na = eval(concat(Str(a), Str(vi[i])))), ok = 1; break; ); ); if (!ok, print("end of sequence"); return(); ); a = na; print1(a, ", "); ); } \\ Michel Marcus, May 11 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. Lowell, May 10 2014
EXTENSIONS
More terms from Michel Marcus, May 11 2014
STATUS
approved