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%I #17 Sep 08 2022 08:46:19
%S 83,811,823,829,853,859,883,8101,8167,8179,8191,8233,8263,8269,8293,
%T 8311,8317,8353,8389,8419,8431,8443,8461,8467,8521,8563,8599,8641,
%U 8647,8677,8719,8761,8821,8839,8863,8887,8929,8941,8971,81013,81019,81031,81049,81097
%N Primes obtained from other primes by prefixing an 8.
%C Except a(1), all the terms in this sequence are congruent to 1 mod 3.
%H Robert Israel, <a href="/A290407/b290407.txt">Table of n, a(n) for n = 1..10000</a>
%e 823 is in the sequence because it is a prime obtained by prefixing an 8 to the prime 23.
%e 8317 is in the sequence because it is a prime obtained by prefixing an 8 to the prime 317.
%p A290407:= n-> (parse(cat(8, ithprime(n)))): select(isprime, [seq((A290407 (n), n=1..1000))]);
%t Select[k = 8; Table[FromDigits[Join[IntegerDigits[k], IntegerDigits[Prime[n]]]], {n, 500}], PrimeQ]
%o (PARI) forprime(p = 2,5000, k=eval(concat(8,Str(p))); if(isprime(k), print1(k,", ")));
%o (Magma) [k : p in PrimesUpTo (5000) | IsPrime (k) where k is Seqint (Intseq (p) cat Intseq (8))];
%Y Subsequence of A045714.
%Y Cf. A165555, A167187, A289866, A289867.
%K nonn,base
%O 1,1
%A _K. D. Bajpai_, Jul 30 2017
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