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 A378054 #8 Nov 15 2024 11:17:29
%S A378054 1,60,90,120,144,168,180,210,240,252,280,336,360,420,504,540,560,630,
%T A378054 660,720,840,900,924,990,1008,1056,1080,1092,1200,1260,1320,1404,1440,
%U A378054 1512,1560,1680,1800,1848,1872,1890,1980,2016,2100,2112,2160,2184,2310,2376,2400
%N A378054 Numbers k that divide A378053(k) = gcd(Product_{d|k} (d + 1), Product_{d|k, d>1} (d - 1)).
%C A378054 After the first term a(1) = 1, the next odd term is a(71) = 3465, the next term that is coprime to 6 is a(1058) = 95095, and the next term that is coprime to 30 is a(12174) = 2263261.
%H A378054 Amiram Eldar, <a href="/A378054/b378054.txt">Table of n, a(n) for n = 1..10000</a>
%e A378054 60 is a term since A378053(60) = 166320 = 60 * 2772 is divisible by 60.
%t A378054 Select[Range[2500], And @@ Divisible[{Times @@ ((d = Divisors[#]) + 1), Times @@ (Rest @ d - 1)}, #] &]
%o A378054 (PARI) is(k) = if(k == 1, 1, my(d = divisors(k)); !(gcd(prod(k=1, #d, d[k]+1), prod(k=2, #d, d[k]-1)) % k));
%Y A378054 Intersection of A056954 and A355331.
%Y A378054 A378055 is a subsequence.
%Y A378054 Cf. A020696, A377484, A378053, A378058.
%K A378054 nonn
%O A378054 1,2
%A A378054 _Amiram Eldar_, Nov 15 2024