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 A320866 #15 Feb 06 2020 15:28:15 %S A320866 5,7,13,17,19,37,59,67,97,127,173,193,223,233,277,359,379,439,499,563, %T A320866 569,599,607,631,653,691,733,769,811,821,829,877,919,929,937,967,1009, %U A320866 1019,1087,1093,1163,1193,1213,1223,1229,1297,1319,1373,1399,1423,1481,1483,1559,1571,1597,1613,1619,1627,1657,1699,1733,1777 %N A320866 Primes such that p + digitsum(p, base 4) is again a prime. %C A320866 Such primes exist only for even bases b. See A243441, A320867, A320868 and A048519 for the analog in base 2, 6, 8 and 10, respectively. Also, as in base 10, there are no such primes (except 5 and 7) when + is changed to -, see comment in A243442. %H A320866 Harvey P. Dale, <a href="/A320866/b320866.txt">Table of n, a(n) for n = 1..1000</a> %e A320866 5 = 4 + 1 = 11[4] (in base 4), and 5 + 1 + 1 = 7 is again prime. %t A320866 Select[Prime[Range[300]],PrimeQ[#+Total[IntegerDigits[#,4]]]&] (* _Harvey P. Dale_, Feb 06 2020 *) %o A320866 (PARI) forprime(p=1,1999,isprime(p+sumdigits(p,4))&&print1(p",")) %Y A320866 Cf. A047791, A048519 (base 10 analog), A048520, A006378, A107740, A243441 (base 2 analog: p + Hammingweight(p) is prime), A243442 (analog for p - Hammingweight(p)), A320867 (analog for base 6), A320868 (analog for base 8). %K A320866 nonn,base %O A320866 1,1 %A A320866 _M. F. Hasler_, Nov 06 2018