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 A387161 #7 Aug 28 2025 17:25:55
%S A387161 2,14,26,62,74,86,122,134,146,152,176,182,206,212,224,254,272,290,302,
%T A387161 314,326,338,368,386,422,428,434,446,476,542,554,566,578,590,626,632,
%U A387161 644,656,662,674,680,722,734,752,782,794,812,842,848,854,866,890,914,920,926,974,1046,1058,1082,1088,1094,1136,1154
%N A387161 Numbers k for which A324644(k)/A324198(k) = 3.
%H A387161 Antti Karttunen, <a href="/A387161/b387161.txt">Table of n, a(n) for n = 1..10000</a>
%H A387161 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%H A387161 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%o A387161 (PARI)
%o A387161 A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
%o A387161 is_A387161(n) = { my(u=A276086(n)); (gcd(sigma(n), u)==3*gcd(n, u)); };
%Y A387161 Subsequences: A387163 (terms whose abundancy >= 3).
%Y A387161 Cf. A000203, A276086, A324198, A324644, A351458.
%Y A387161 Cf. also A364286.
%K A387161 nonn,new
%O A387161 1,1
%A A387161 _Antti Karttunen_, Aug 28 2025