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 A078586 #21 Jul 05 2025 01:25:59
%S A078586 3,21,231,4389,100947,3129357,134562351,6324430497,373141399323,
%T A078586 25000473754641,1775033636579511,140227657289781369,
%U A078586 11638895555051853627,1198806242170340923581,128272267912226478823167,16290578024852762810542209,2134065721255711928181029379
%N A078586 a(n) is the product of the first n primes of the form 4k+3.
%C A078586 a(n)+2 is a prime for n=1,2,3,4,8,10,12,17,19,22,23,53.
%C A078586 Product of first n primes that are also Gaussian primes; product of first n primes that are not of the form x^2+y^2.
%H A078586 T. D. Noe, <a href="/A078586/b078586.txt">Table of n, a(n) for n = 1..100</a>
%t A078586 maxN=15; pLst={}; k=0; While[Length[pLst]<maxN, k++; If[PrimeQ[4k-1], AppendTo[pLst, 4k-1]]]; lst=Drop[FoldList[Times, 1, pLst], 1]
%o A078586 (PARI) a(n)=my(t=1); forprime(p=2,,if(p%4==3, t*=p; if(n--<1,return(t)))) \\ _Charles R Greathouse IV_, Mar 09 2014
%Y A078586 Cf. A002110, A006278, A038347.
%Y A078586 Partial products of A002145.
%K A078586 easy,nonn
%O A078586 1,1
%A A078586 _T. D. Noe_, Dec 01 2002