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 A300399 #27 Mar 27 2018 05:53:50 %S A300399 2,24,254,2508,25015,250014,2500283,25000402,250002505,2500005319, %T A300399 25000014226,250000051446 %N A300399 a(n) = number of primes that end in 7 among the first 10^n primes. %F A300399 a(n) = A185714(A006988(n)). - _Michel Marcus_, Mar 20 2018 %e A300399 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 7. %o A300399 (PARI) a(n) = #select(x->((x % 10) == 7), primes(10^n)); \\ _Michel Marcus_, Mar 07 2018 %Y A300399 Cf. A006988, A030432, A185714, A300397, A300398, A300400. %K A300399 nonn,base,more %O A300399 1,1 %A A300399 _G. L. Honaker, Jr._, Mar 05 2018 %E A300399 a(3)-a(8) from Chuck Gaydos %E A300399 a(9) from _Jon E. Schoenfield_, Mar 20 2018 %E A300399 a(10)-a(12) from _Giovanni Resta_, Mar 27 2018