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 A361566 #27 Mar 18 2023 19:12:34 %S A361566 1,2,1,1,1,2,1,1,1,2,1,2,1,2,1,1,1,2,1,2,1,2,1,1,1,2,1,2,1,2,1,1,1,2, %T A361566 1,1,1,2,1,2,1,2,1,2,1,2,1,1,1,2,1,2,1,2,1,2,1,2,1,1,1,2,1,1,1,2,1,2, %U A361566 1,2,1,2,1,2,1,2,1,2,1,1,1,2,1,2,1,2,1,2 %N A361566 a(n) is the denominator of the median of divisors of n. %C A361566 a(n) = 2 if n is in A139710, otherwise a(n) = 1. - _Robert Israel_, Mar 15 2023 %H A361566 Winston de Greef, <a href="/A361566/b361566.txt">Table of n, a(n) for n = 1..10000</a> %H A361566 <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a> %F A361566 a(n) = denominator((A033676(n) + A033677(n))/2). %F A361566 Except for p = 2 and k = 1, a(p^k) = 1, if p is a prime. %e A361566 a(9) = 1 since the divisors of 9 are 1, 3, 9, and their median is 3. %e A361566 a(12) = 2 since the divisors of 12 are 1, 2, 3, 4, 6, 12, and their median is 7/2. %t A361566 a[n_]:=Denominator[Median[Divisors[n]]]; Array[a,88] %o A361566 (PARI) a(n) = my(d=divisors(n), m=#d+1); denominator((d[m\2] + d[m-m\2])/2); \\ _Michel Marcus_, Mar 16 2023 %Y A361566 Cf. A027750, A033676, A033677, A071090, A139710, A139711, A361565 (numerator). %K A361566 nonn,frac %O A361566 1,2 %A A361566 _Stefano Spezia_, Mar 15 2023