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 A107120 #22 Jul 31 2025 22:02:47
%S A107120 162,242,291,371,461,515,2419,2815,11874,64751,81927,264961,276184,
%T A107120 757155,2537825,7717729,9548491,14738827,19728438,19728446,19728464,
%U A107120 23695527,77362954,269776516,269776523,269776532,358399327,2385883646,59955748691,67893872935,848472784869
%N A107120 Numbers m such that pi(m) = prime(d_1*d_2*...*d_k) where d_1 d_2 ... d_k is the decimal expansion of m.
%C A107120 A107121 is a subsequence of this sequence (see the comments line of A107121).
%C A107120 a(32) > 7*10^14, if it exists. - _Giovanni Resta_, Jun 01 2020
%C A107120 The sequence is finite as pi(m) >= pi(10^(k-1)) grows faster than prime(9^k) >= prime(d_1*d_2*...*d_k). - _Max Alekseyev_, Dec 30 2024
%e A107120 23695527 is in the sequence because pi(23695527)=prime(2*3*6*9*5*5*2*7).
%t A107120 Do[h = IntegerDigits[m]; l = Length[h]; If[Min[h] > 0 && PrimePi[m] == Prime[Product[h[[k]], {k, l}]], Print[m]], {m, 52000000}]
%Y A107120 Cf. A097223, A107121.
%K A107120 nonn,base,fini
%O A107120 1,1
%A A107120 _Farideh Firoozbakht_, May 13 2005
%E A107120 a(23)-a(28) from _Donovan Johnson_, Jul 12 2010
%E A107120 a(29)-a(31) from _Giovanni Resta_, Jun 01 2020