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%I #17 Feb 13 2020 00:12:27
%S 2,17,257,337,881,1297,2657,6577,10657,14897,16561,28817,65537,65617,
%T 66161,80177,83777,149057,160001,166561,260017,280097,331777,391921,
%U 394721,411361,463537,596977,614657,621217,847601,1055137,1336337,1342897,1682017,1763137
%N Semi-octavan primes: primes of the form x^4 + y^8.
%H Charles R Greathouse IV, <a href="/A291206/b291206.txt">Table of n, a(n) for n = 1..10000</a>
%H A. J. C. Cunningham, <a href="/wiki/File:High_quartan_factorisations_and_primes.pdf">High quartan factorisations and primes</a>, Messenger of Mathematics 36 (1907), pp. 145-174.
%e a(1) = 1^4 + 1^8 = 2.
%e a(2) = 2^4 + 1^8 = 17.
%e a(3) = 1^4 + 2^8 = 257.
%e a(4) = 3^4 + 2^8 = 337.
%o (PARI) list(lim)=my(v=List([2]),x4,t); for(x=1, sqrtnint(lim\=1,4), x4=x^4; forstep(y=x%2+1, sqrtnint(lim-x4,8), 2, if(isprime(t=x4+y^8), listput(v, t)))); Set(v)
%Y Subsequence of A002645 and hence of A028916. A006686 is a subsequence.
%K nonn
%O 1,1
%A _Charles R Greathouse IV_, Aug 21 2017
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