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 A300400 #25 Mar 27 2018 05:54:56 %S A300400 2,24,246,2491,25009,249940,2499751,25000026,249997694,2499999305, %T A300400 24999974939,249999962302 %N A300400 a(n) = number of primes that end in 9 among the first 10^n primes. %H A300400 Caldwell and Honaker, <a href="https://primes.utm.edu/curios/page.php/2499751.html">Prime Curios!</a> %F A300400 a(n) = A185715(A006988(n)). - _Michel Marcus_, Mar 20 2018 %e A300400 a(1) = 2 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there are two primes ending in 9. %o A300400 (PARI) a(n) = #select(x->((x % 10) == 9), primes(10^n)); \\ _Michel Marcus_, Mar 07 2018 %Y A300400 Cf. A006988, A030433, A185715, A300397, A300398, A300399. %K A300400 nonn,base,more %O A300400 1,1 %A A300400 _G. L. Honaker, Jr._, Mar 05 2018 %E A300400 a(3)-a(8) from Chuck Gaydos %E A300400 a(9) from _Jon E. Schoenfield_, Mar 20 2018 %E A300400 a(10)-a(12) from _Giovanni Resta_, Mar 27 2018