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 A296059 #29 Apr 25 2018 12:02:19 %S A296059 4,7,16,43,58,106,160,229,628,1579,3805,16153,31420 %N A296059 Numbers k such that (10^k/8 + 1)/9 is prime. %C A296059 Equivalently, numbers k such that (10^k + 8)/72 is prime. %C A296059 a(12) > 15000. - _Robert G. Wilson v_, Dec 09 2017 %C A296059 a(14) > 10^5. - _Robert Price_, Apr 24 2018 %e A296059 139, 138889, and 138888888888889 are prime, so 4, 7, and 16 are in the sequence. %t A296059 Select[Range[2000], PrimeQ[(10^#/8 + 1)/9] &] (* _Michael De Vlieger_, Dec 06 2017 *) %t A296059 ParallelMap[ If[ PrimeQ[(10^#/8 +1)/9], #, Nothing] &, Range@ 10000] (* _Robert G. Wilson v_, Dec 08 2017 *) %o A296059 (PARI) isok(k) = (k>2) && isprime((10^k/8 + 1)/9); \\ _Michel Marcus_, Dec 05 2017 %Y A296059 Cf. A296029. %K A296059 nonn,more %O A296059 1,1 %A A296059 _Patrick A. Thomas_, Dec 04 2017 %E A296059 a(8)-a(11) from _Jon E. Schoenfield_, Dec 04 2017 %E A296059 a(12)-a(13) from _Robert Price_, Apr 24 2018