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 A091708 #16 Jul 21 2015 06:12:48
%S A091708 1,9,68,549,4819,43506,397756,3681943,34344296,322199867,3036544958,
%T A091708 28722439343,272501681533,2591959274190
%N A091708 Number of primes less than 10^n having at least one digit 7.
%e A091708 a(1) = 1 because of the 4 primes less than 10^1, 1 has at least one digit 7.
%t A091708 NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; c = 0; p = 1; Do[ While[ p = NextPrim[p]; p < 10^n, If[ Position[ IntegerDigits[p], 7] != {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* _Robert G. Wilson v_, Feb 02 2004 *)
%t A091708 Table[Count[Prime[Range[PrimePi[10^n]]],_?(DigitCount[#,10,7]>0&)],{n,12}] (* _Harvey P. Dale_, Mar 03 2013 *)
%Y A091708 a(n) + A091641(n) = A006880(n).
%Y A091708 Cf. A091644, A091645, A091646, A091647, A090705, A090706, A091707, A091709, A091710.
%K A091708 nonn,base
%O A091708 1,2
%A A091708 _Enoch Haga_, Jan 30 2004
%E A091708 Edited and extended by _Robert G. Wilson v_, Feb 02 2004
%E A091708 3 more terms from _Ryan Propper_, Aug 21 2005
%E A091708 a(13) from _Robert Price_, Nov 11 2013
%E A091708 a(14) from _Giovanni Resta_, Jul 21 2015