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 A221220 #26 Jun 12 2021 09:07:40
%S A221220 6,12,18,21,22,24,33,36,39,44,46,48,51,54,58,63,66,70,72,82,88,92,93,
%T A221220 96,99,108,111,115,116,117,132,133,140,141,142,144,147,153,154,159,
%U A221220 162,164,165,166,176,177,182,184,187,189,192,198,201,205,210,216,219
%N A221220 Numbers with more than one prime factor such that concatenation of its prime factors (without multiplicity) is a prime.
%e A221220 Prime factors of 140 are 2, 5, and 7 and 257 is prime, so 140 is a term.
%t A221220 Select[Range[220],Length[x=First/@FactorInteger[#]]>1&&PrimeQ[FromDigits[Flatten[IntegerDigits[x]]]]&]
%o A221220 (Python)
%o A221220 from sympy import isprime, primefactors
%o A221220 def ok(n):
%o A221220 pf = primefactors(n)
%o A221220 if len(pf) < 2: return False
%o A221220 return isprime(int("".join(str(p) for p in pf)))
%o A221220 print(list(filter(ok, range(2, 220)))) # _Michael S. Branicky_, Jun 12 2021
%Y A221220 Cf. A024619, A046411.
%K A221220 nonn,base,less
%O A221220 1,1
%A A221220 _Jayanta Basu_, Jun 04 2013