This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A107121 #18 Jul 31 2025 19:31:30
%S A107121 461,264961,9548491,14738827
%N A107121 Numbers m such that m=prime(prime(d_1*d_2*...*d_k)) where d_1 d_2 ... d_k is the decimal expansion of m.
%C A107121 If m is in the sequence then pi(m) = prime(d_1*d_2*...*d_k) where d_1 d_2 ... d_k is the decimal expansion of m, so this sequence is a subsequence of A107120.
%C A107121 The sequence is finite as m >= 10^(k-1) grows faster than prime(prime(9^k)) >= prime(prime(d_1*d_2*...*d_k)). If it exists, a(5) > 10^14. - _Max Alekseyev_, Dec 30 2024
%e A107121 14738827 is in the sequence because 14738827=prime(prime(1*4*7*3*8*8*2*7)).
%t A107121 Do[h= IntegerDigits[Prime[m]];l = Length[h];If[Min[h] > 0 && m == Prime[Product[h[[k]], {k, l}]], Print[Prime [m]]], {m, 20000000}]
%Y A107121 Cf. A097223, A107120, A107122.
%K A107121 base,fini,nonn,more
%O A107121 1,1
%A A107121 _Farideh Firoozbakht_, May 13 2005