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 A056954 #22 Nov 13 2024 08:30:24
%S A056954 1,30,60,90,105,120,132,144,168,180,210,240,252,264,280,336,360,380,
%T A056954 396,420,495,504,520,528,540,546,552,560,612,616,630,660,720,728,756,
%U A056954 760,792,840,858,870,900,924,990,1008,1040,1050,1056,1080,1092,1104
%N A056954 Numbers k such that k^2 divides A056819(k).
%C A056954 From _Amiram Eldar_, Nov 12 2024: (Start)
%C A056954 Equivalently, numbers k that divide A377484(k) = Product_{d|k, d>1} (d - 1).
%C A056954 After the first term a(1) = 1, the next odd term is a(5) = 105, the next term that is coprime to 6 is a(228) = 6545, and the next term that is coprime to 30 is a(574) = 19019. (End)
%H A056954 Amiram Eldar, <a href="/A056954/b056954.txt">Table of n, a(n) for n = 1..10000</a>
%e A056954 30 is a term because 30^2 divides A056819(30) = 5320224000.
%t A056954 Select[Range[1000], Divisible[Times @@ (Rest@ Divisors[#] - 1), #] &] (* _Amiram Eldar_, Nov 12 2024 *)
%o A056954 (PARI) is(k) = if(k == 1, 1, my(d = divisors(k)); !(prod(i = 2, #d, d[i]-1) % k)); \\ _Amiram Eldar_, Nov 12 2024
%Y A056954 Cf. A056819, A377484.
%Y A056954 A377949 is a subsequence.
%Y A056954 Similar sequences: A355331, A377950, A377952.
%K A056954 nonn,easy
%O A056954 1,2
%A A056954 _Leroy Quet_, Sep 06 2000