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 A291206 #19 May 01 2025 13:00:13
%S A291206 2,17,257,337,881,1297,2657,6577,10657,14897,16561,28817,65537,65617,
%T A291206 66161,80177,83777,149057,160001,166561,260017,280097,331777,391921,
%U A291206 394721,411361,463537,596977,614657,621217,847601,1055137,1336337,1342897,1682017,1763137
%N A291206 Semi-octavan primes: primes of the form x^4 + y^8.
%H A291206 Charles R Greathouse IV, <a href="/A291206/b291206.txt">Table of n, a(n) for n = 1..10000</a>
%H A291206 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 A291206 a(1) = 1^4 + 1^8 = 2.
%e A291206 a(2) = 2^4 + 1^8 = 17.
%e A291206 a(3) = 1^4 + 2^8 = 257.
%e A291206 a(4) = 3^4 + 2^8 = 337.
%t A291206 Take[Select[Flatten[Table[x^4+y^8,{x,40},{y,40}]],PrimeQ]//Union,40] (* _Harvey P. Dale_, May 01 2025 *)
%o A291206 (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 A291206 Subsequence of A002645 and hence of A028916. A006686 is a subsequence.
%K A291206 nonn
%O A291206 1,1
%A A291206 _Charles R Greathouse IV_, Aug 21 2017