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 A383483 #27 May 16 2025 14:32:48 %S A383483 3,15,5919,118719,179871,33750303 %N A383483 Numbers k such that k = sigma(m)-m where m = sigma(3*k)-3*k. %C A383483 S. I. Dimitrov introduced the notion of (alpha, beta)-amicable pairs. %H A383483 S. I. Dimitrov, <a href="https://arxiv.org/abs/2408.07387">Generalizations of amicable numbers</a>, arXiv:2408.07387 [math.NT], 2024. %F A383483 We say that the numbers m and n form an (alpha, beta)-amicable pair if sigma(alpha*n)-alpha*n=m and sigma(beta*m)-beta*m=n, where alpha and beta are positive integers, and sigma(n) is the sum of the divisors of n. %e A383483 For alpha=1, beta=3 we have (3, 4), (15, 33), (5919, 7905). %e A383483 Here (3, 4) is such a pair because 3=sigma(4)-4 and 4=sigma(3*3)-3*3. %o A383483 (PARI) isok(k) = my(m = sigma(3*k) - 3*k); if (m>0, sigma(m) - m == k); \\ _Michel Marcus_, Apr 28 2025 %Y A383483 Cf. A063990, A259180, A383239. %K A383483 nonn,more %O A383483 1,1 %A A383483 _S. I. Dimitrov_, Apr 28 2025 %E A383483 a(4)-a(6) from _Michel Marcus_, Apr 28 2025