A342953 a(n) is the least prime that starts a string of exactly n primes p_1, p_2, ... p_n where p_{i+1} = A258881(p_i), but A258881(p_n) is not prime.
2, 13, 11, 19, 499, 8851471
Offset: 1
Examples
a(3) = 11 because 11, A258881(11) = 13, and A258881(13) = 23 are prime.
Programs
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Maple
f:= proc(n) option remember; local t,x; x:= n + add(t^2,t=convert(n,base,10)); if not isprime(x) then 1 else 1+procname(x) fi end proc: V:= Vector(6): count:= 0: p:= 1: while count < 6 do p:= nextprime(p); v:= f(p); if v <= N and V[v] = 0 then V[v]:= p; count:= count+1 fi od: convert(V,list);
Comments