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 A380303 #12 May 28 2025 01:12:06
%S A380303 1,6,10,11,14,15,16,17,20,21,23,24,25,26,28,30,31,33,34,35,38,39,40,
%T A380303 41,42,44,46,47,51,52,53,54,55,56,57,58,59,60,62,63,65,66,69,70,71,74,
%U A380303 76,77,78,79,83,84,85,86,87,88,89,90,92,93,94,95,96,97,99,102,103,105,107,108,110,111,112,113,114,115,117,118,119,120,123,124,125,126,127,130,131,132,135,136,138,139,140,141,142,143,145,147,150
%N A380303 Numbers m such that GCD of the solutions x to sigma(x) = sigma(m) are setwise coprime.
%H A380303 Amiram Eldar, <a href="/A380303/b380303.txt">Table of n, a(n) for n = 1..10000</a>
%H A380303 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%F A380303 Union of {1} and the set difference of A206036 and A241481.
%o A380303 (PARI) isok(k) = if(k == 1, 1, my(v = invsigma(sigma(k))); #v > 1 && gcd(v) == 1); \\ _Amiram Eldar_, May 28 2025, using _Max Alekseyev_'s invphi.gp (see links).
%Y A380303 Cf. A206036, A211656, A241480, A241481, A241625, A380304.
%K A380303 nonn
%O A380303 1,2
%A A380303 _Max Alekseyev_, Jan 19 2025