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 A118690 #13 Mar 07 2024 08:52:23
%S A118690 4,6,9,22,33,55,77,91,123,141,177,213,217,321,411,717,721,771,1135,
%T A118690 1157,1315,1351,1513,1517,1751,3151,5131,5311,7115,11157,11215,11521,
%U A118690 11611,11751,12115,12151,15117,15711,17151,21151,51211,57111,61111,75111
%N A118690 Semiprimes for which both the sum and the product of the digits is also a semiprime.
%H A118690 Vincenzo Librandi, <a href="/A118690/b118690.txt">Table of n, a(n) for n = 1..128</a>
%e A118690 91 is in the sequence because (1) it is a semiprime, (2) the sum of its digits is 9+1=10, (3) the product of its digits is 1*9=9 and (4) both 9 and 10 are semiprimes.
%t A118690 spQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; fQ[n_] := Block[{id = IntegerDigits@n}, spQ@n && spQ[Plus @@ id] && spQ[Times @@ id]]; Select[ Range@111172, fQ@# &] (* _Robert G. Wilson v_, Jun 15 2006 *)
%t A118690 Select[Range[76000],Thread[PrimeOmega[{#,Total[IntegerDigits[#]],Times@@ IntegerDigits[#]}]] == {2,2,2}&] (* _Harvey P. Dale_, Jul 26 2022 *)
%Y A118690 Cf. A001358.
%K A118690 base,nonn
%O A118690 1,1
%A A118690 Luc Stevens (lms022(AT)yahoo.com), May 20 2006
%E A118690 More terms from _Robert G. Wilson v_, Jun 15 2006