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 A319858 #21 Oct 26 2018 08:17:23 %S A319858 0,8,8,1,7,1,5,2,2,3,3,1,3,0,2,2,3,0,4,0,2,2,4,0,2,1,1,2,3,0,3,0,3,2, %T A319858 1,0,4,1,3,0,2,0,5,0,1,1,3,1,1,1,0,1,2,0,4,1,1,1,3,0,3,0,1,1,1,1,4,1, %U A319858 0,0,5,0,2,0,2,0,1,0,4,0,1,1,3,1,1,0,2,1,3,0,2,0,2,2,1,0,3,0,0,0 %N A319858 a(n) is the number of values of m in the interval [2,10] such that the base-m expansion of n, interpreted as a base-10 number, yields a prime. %e A319858 a(31)=3 because 31 yields primes for 3 bases in [2,10]: 31 = 11111_2 = 1011_3 = 133_4 = 111_5 = 51_6 = 43_7 = 37_8 = 34_9 = 31_10, and of the decimal numbers 11111, 1011, 133, 111, 51, 43, 37, 34, and 31, the 3 primes are 43, 37, and 31. %t A319858 Array[Count[FromDigits /@ IntegerDigits[#, Range[2, 10]], _?PrimeQ] &, 105] (* _Michael De Vlieger_, Oct 11 2018 *) %o A319858 (PARI) a(n) = sum(b=2, 10, isprime(fromdigits(digits(n, b), 10))); \\ _Michel Marcus_, Sep 30 2018 %Y A319858 Cf. A052026 (where a(n) is 0). %K A319858 nonn,base,easy %O A319858 1,2 %A A319858 _Anton Deynega_, Sep 29 2018