Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #11 Apr 25 2022 08:11:10
%S 1,1,3,1,1,3,1,1,3,1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,
%T 1,3,1,1,3,1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,1,3,1,1,
%U 3,1,1,3,1,1,3,1,3,1,3,3,1,3,3,1,3,3,1,3,3,1,3,1,3,1,1,3,1,1,3,1,1,3,1,1,3,1
%N The largest proper divisor of A276086(2*n) reduced modulo 4, where A276086(n) the primorial base exp-function.
%H Antti Karttunen, <a href="/A353517/b353517.txt">Table of n, a(n) for n = 0..65537</a>
%H <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%F a(n) = A353516(2*n) = A010873(A324895(2*n)).
%F For n >= 1, a(n) = (A353487(n) * A353527(n)) mod 4.
%F For n >= 1, a(n) = A353487(n-1). [See A353516 for a proof]
%o (PARI)
%o A032742(n) = if(1==n,n,n/vecmin(factor(n)[,1]));
%o A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
%o A324895(n) = A032742(A276086(n));
%o A353517(n) = (A324895(2*n)%4);
%Y Even bisection of A353516. Sequence A353487 shifted one term right.
%Y Cf. A010873, A032742, A276086, A324895, A353527.
%K nonn
%O 0,3
%A _Antti Karttunen_, Apr 24 2022