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 A320869 #9 Nov 08 2018 03:27:24 %S A320869 17,19,23,29,31,53,59,89,127,149,151,157,179,181,211,223,241,251,263, %T A320869 269,331,359,367,397,419,431,449,457,461,463,487,541,563,571,593,599, %U A320869 601,631,659,661,701,733,761,769,809,811,839,907,911,941,971,997,1049,1087,1109,1171,1201,1237,1283,1289,1291 %N A320869 Primes such that p + digitsum(p, base 16) is again a prime. %C A320869 Such primes exist only for an even base b. See A048519, A243441, A320866, A320867 and A320868 for the analog in base 10, 2, 4, 6 and 8, respectively. Also, as in base 10, there are no such primes when + is changed to -, see comment in A243442. %H A320869 Robert Israel, <a href="/A320869/b320869.txt">Table of n, a(n) for n = 1..10000</a> %e A320869 17 = 16 + 1 = 11[16] (in base 16), and 17 + 1 + 1 = 19 is again prime. %p A320869 digsum:= (n,b) -> convert(convert(n,base,b),`+`): %p A320869 select(p -> isprime(p) and isprime(p+digsum(p,16)), [2,seq(i,i=3..1000,2)]); # _Robert Israel_, Nov 07 2018 %o A320869 (PARI) forprime(p=1,1999,isprime(p+sumdigits(p,16))&&print1(p",")) %Y A320869 Cf. A047791, A048519 (base 10 analog), A048520, A006378, A107740, A243441 (base 2 analog: p + Hammingweight(p) is prime), A243442 (analog for p - Hammingweight(p)), A320866 (analog for base 4), A320867 (analog for base 6), A320868 (analog for base 8). %K A320869 nonn,base %O A320869 1,1 %A A320869 _M. F. Hasler_, Nov 06 2018