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A069612 a(1) = 19 (the smallest prime ending in a 9) and a(n+1) = smallest prime ending in a(n).

%I A069612 #18 Jun 23 2022 13:50:08
%S A069612 19,419,5419,35419,435419,11435419,111435419,9111435419,89111435419,
%T A069612 1389111435419,81389111435419,381389111435419,15381389111435419,
%U A069612 3315381389111435419,153315381389111435419,22153315381389111435419,2022153315381389111435419
%N A069612 a(1) = 19 (the smallest prime ending in a 9) and a(n+1) = smallest prime ending in a(n).
%H A069612 Michael S. Branicky, <a href="/A069612/b069612.txt">Table of n, a(n) for n = 1..367</a> (terms 1..300 from Harvey P. Dale)
%t A069612 w=9; Table[w; i=1; While[PrimeQ[ToExpression[StringJoin[ToString[i], ToString[w]]]]==False, i++ ]; w=ToExpression[StringJoin[ToString[i], ToString[w]]], {32}]
%t A069612 nxt[n_]:=Module[{c=10^IntegerLength[n],x=1},While[!PrimeQ[c*x+n],x++];c*x+n]; NestList[nxt,19,15] (* _Harvey P. Dale_, Sep 25 2013 *)
%o A069612 (Python)
%o A069612 from sympy import isprime
%o A069612 from itertools import count, islice
%o A069612 def agen(an=19):
%o A069612     while True:
%o A069612         yield an
%o A069612         pow10 = 10**len(str(an))
%o A069612         for t in count(pow10+an, step=pow10):
%o A069612             if isprime(t):
%o A069612                 an = t
%o A069612                 break
%o A069612 print(list(islice(agen(), 17))) # _Michael S. Branicky_, Jun 23 2022
%Y A069612 Cf. A053582, A053583, A053584.
%K A069612 nonn,base
%O A069612 1,1
%A A069612 _Amarnath Murthy_, Mar 27 2002
%E A069612 More terms from _Hans Havermann_, Jun 06 2002