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 A217265 #9 Oct 02 2012 08:32:09 %S A217265 21249,33271,89937,146461,147833,148519,164297,175257,211631,216953, %T A217265 234269,254849,261023,269941,311229,318033,348823,377001,390447, %U A217265 520209,561491,848239,941679,943679,957447,960957,1012879,1110159,1221431,1410399,1525203,1681729 %N A217265 Numbers with 4 or more prime factors (with multiplicity) such that every concatenation of their prime factors is prime. %e A217265 21249 is 3*3*3*787. 333787, 337873, 378733 and 787333 are all prime, so 21249 is in the sequence. %Y A217265 Cf. A217263, A217264, A180679, A181559. %K A217265 nonn,base %O A217265 1,1 %A A217265 _Dmitri Kamenetsky_, Sep 29 2012