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 A059047 #19 Jan 05 2025 19:51:36 %S A059047 77,611,1073,2033,5293,6031,9983,13969,15947,23489,25241,40301,49901, %T A059047 50249,51101,56759,65017,71677,85079,97217,97783,98099,99101,131237, %U A059047 142091,160133,165101,180767,189281,210367,213053,228719,259741,303239 %N A059047 Numbers x such that sigma(x)-x divides x-1, other than prime powers. %C A059047 Primes and prime powers (A000961) also satisfy this equation. A059046 is the union of A000961 and A059047. These numbers are related to hyperperfect numbers (A034897) in the cited paper by te Riele. %H A059047 Donovan Johnson, <a href="/A059047/b059047.txt">Table of n, a(n) for n = 1..5263</a> (terms < 10^11) %H A059047 H. J. J. te Riele, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/22-1/teriele.pdf">Rules for constructing hyperperfect numbers</a>, Fibonacci Quarterly, 22(1)1984, 50-60. See equation (3), the set M*. %e A059047 For x=77, sigma(77)=96, 96-77=19, which divides 77-1. %o A059047 (PARI) is(n)=n>1 && !isprimepower(n) && (n-1)%(sigma(n)-n)==0 \\ _Charles R Greathouse IV_, Oct 21 2015 %Y A059047 Cf. A059046, A000203, A000961, A034897. %K A059047 nonn %O A059047 1,1 %A A059047 _Jud McCranie_, Dec 18 2000 %E A059047 Offset corrected by _Donovan Johnson_, Nov 03 2011