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 A341045 #15 Feb 04 2021 07:26:21 %S A341045 1,4,6,28,45,120,496,672,6048,8128,14421,30240,32760,523776,2178540, %T A341045 23569920,26409026,29270772,30685402,33550336,45532800 %N A341045 Numbers k such that k divides A318996(k). %e A341045 a(2) = 4 is a term because A318996(4) = 4 is divisible by 4. %e A341045 a(3) = 6 is a term because A318996(6) = 0 is divisible by 6. %p A341045 f:= proc(n) local s,D,t; %p A341045 D:= numtheory:-divisors(n); %p A341045 s:= convert(D,`+`); %p A341045 add(s mod t, t=D) %p A341045 end proc: %p A341045 select(t -> f(t) mod t = 0, [$1..20000]); %o A341045 (PARI) f(n) = my(sn = sigma(n)); sumdiv(n, d, sn % d); \\ A318996 %o A341045 isok(k) = !(f(k) % k); \\ _Michel Marcus_, Feb 03 2021 %Y A341045 Contains A007691. %Y A341045 Cf. A318996. %K A341045 nonn,more %O A341045 1,2 %A A341045 _J. M. Bergot_ and _Robert Israel_, Feb 03 2021