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 A118697 #6 Mar 07 2024 08:52:19
%S A118697 4,6,9,10,21,34,65,87,123,321,543,789,901,1234,4321,8765,34567,56789,
%T A118697 98765,654321,876543,901234,1234567,7654321,7890123,10987654,21098765,
%U A118697 567890123,12345678901,54321098765,76543210987,87654321098
%N A118697 Semiprimes with consecutive digits.
%C A118697 Digits can be in ascending or descending order. After 9 comes 0.
%C A118697 The number of semiprimes with n consecutive digits: 3,5,5,3,3,3,3,2,1,0,4,0,2,0,2,1,1,1,1,0,1,2,0,1,0,0,2,1,0,0,1,1,1,0,0,0,0,2,1,0,1,0,0,0,2,1,0,0,0,0,..., . - _Robert G. Wilson v_, Jun 16 2006
%t A118697 spQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; f[n_] := Block[{u = Range@n, d = Reverse@ Range@n, t = Table[1, {n}]}, Select[ Drop[ Union@ Flatten@ Table[ FromDigits /@ Mod[{u, d} + {i*t, i*t}, 10], {i, 10}], 2], spQ@# &]]; Array[f, 13] // Flatten (* _Robert G. Wilson v_, Jun 16 2006 *)
%Y A118697 Cf. A001358.
%K A118697 base,nonn
%O A118697 1,1
%A A118697 Luc Stevens (lms022(AT)yahoo.com), May 20 2006
%E A118697 More terms from _Robert G. Wilson v_, Jun 16 2006