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 A361786 #9 Mar 24 2023 11:12:55
%S A361786 1,3,5,6,7,9,11,12,13,14,15,17,19,21,22,23,25,27,28,29,30,31,33,35,37,
%T A361786 38,39,41,42,43,44,45,46,47,49,51,53,54,55,56,57,59,60,61,62,63,65,66,
%U A361786 67,69,70,71,73,75,76,77,78,79,81,83,84,85,86,87,89,91,92,93,94,95,96,97,99
%N A361786 Bi-unitary arithmetic numbers: numbers for which the arithmetic mean of the bi-unitary divisors is an integer.
%C A361786 First differs from A361386 at n = 35.
%C A361786 Number k such that A286324(k) divides A188999(k).
%H A361786 Amiram Eldar, <a href="/A361786/b361786.txt">Table of n, a(n) for n = 1..10000</a>
%e A361786 6 is a term since the arithmetic mean of its bi-unitary divisors, {1, 2, 3, 6}, is 3 which is an integer.
%t A361786 f[p_, e_] := If[OddQ[e], (p^(e+1)-1)/((e + 1)*(p-1)), ((p^(e+1)-1)/(p-1)-p^(e/2))/e]; q[1] = True; q[n_] := IntegerQ[Times @@ f @@@ FactorInteger[n]]; Select[Range[100], q]
%o A361786 (PARI) is(n) = {my(f = factor(n), p, e); denominator(prod(i=1, #f~, p = f[i, 1]; e = f[i, 2]; if(e%2, (p^(e+1)-1)/((e + 1)*(p-1)), ((p^(e+1)-1)/(p-1)-p^(e/2))/e))) == 1; }
%Y A361786 Cf. A188999, A222266, A286324.
%Y A361786 Similar sequences: A003601, A103826, A361386.
%K A361786 nonn
%O A361786 1,2
%A A361786 _Amiram Eldar_, Mar 24 2023