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 A353487 #17 Apr 25 2022 08:11:06
%S A353487 1,3,1,1,3,1,1,3,1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,1,
%T A353487 3,1,1,3,1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,1,3,1,1,3,
%U A353487 1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,1,3,1,1,3,1,1,3,1,1,3,1,3
%N A353487 a(n) = A276086(2*n) mod 4, where A276086 is the primorial base exp-function.
%H A353487 Antti Karttunen, <a href="/A353487/b353487.txt">Table of n, a(n) for n = 0..65537</a>
%H A353487 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%F A353487 a(n) = A353486(2*n) = A010873(A276086(2*n)).
%F A353487 a(n) = A353516(2*n + 1).
%F A353487 a(n) = A353517(1+n). [See comments in A353516 for a proof]
%F A353487 For n >= 1, a(n) = (A353517(n) * A353527(n)) mod 4.
%o A353487 (PARI)
%o A353487 A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
%o A353487 A353487(n) = (A276086(2*n)%4);
%Y A353487 Even bisection of A353486. Odd bisection of A353516. Sequence A353517 shifted once left.
%Y A353487 Cf. A010873, A276086, A353465, A353466, A353488, A353489, A353527.
%K A353487 nonn,base
%O A353487 0,2
%A A353487 _Antti Karttunen_, Apr 24 2022