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 A254715 #5 Feb 08 2015 07:18:52 %S A254715 3,4,8,18,55,137,415,941,2854,7743,21959,61545,175817,496688 %N A254715 Number of n-digit semiprimes with semiprime digits (4, 6, 9). %F A254715 a(n) = number of n-digit terms in A107342. %e A254715 a(1) = 3 because there are 3 one-digit semiprimes with semiprime digits: 4,6,9. %e A254715 a(2) = 4 because there are 4 two-digit relevant semiprimes: 46,49,69,94. %e A254715 a(3) = 8 because there are 8 three-digit relevant semiprimes: 446,466,469,649,669,694,699,949. %Y A254715 Cf. A107342. %K A254715 nonn,base %O A254715 1,1 %A A254715 _Zak Seidov_, Feb 06 2015