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 A345765 #19 Jul 04 2021 17:20:37 %S A345765 1806,12642,88494,6030842622,259326232746,11151028008078, %T A345765 468349207181898,479494204347354,20139015908821614,20618250786936222, %U A345765 865977684079329402,886584783838257546,36371531080539016782,37237040415411164286,38123145705045074478,1563975836463177721626 %N A345765 Numbers k with property that for p prime, p | k iff (p - 1) | k. %C A345765 All terms are divisible by 1806. A345975 provides the terms divided by the common factor. %C A345765 1806 is the only squarefree term. %H A345765 Mees de Vries, <a href="/A345765/b345765.txt">Table of n, a(n) for n = 1..126</a> %H A345765 Mees de Vries, <a href="https://github.com/mjdv/saturated-numbers">Code for generating large instances</a> %F A345765 a(n) = 1806*A345975(n). %e A345765 The prime divisors of 1806 are 2, 3, 7, 43. 1806 is divisible by each of 1, 2, 6, 42. The remaining even divisors of 1806 are 14, 86, 602, 1806, and none of 15, 87, 603 or 1807 are prime. %o A345765 (Python) %o A345765 from sympy import isprime, divisors, primefactors %o A345765 def a(n): return all(n % (div + 1) == 0 for div in divisors(n) if isprime(div + 1)) and all(n % (div - 1) == 0 for div in primefactors(n)) %o A345765 (Python) See De Vries link. %Y A345765 Subsequence of A124240, which only has the requirement p | k implies (p - 1) | k. %Y A345765 Cf. A345975. %K A345765 nonn %O A345765 1,1 %A A345765 _Mees de Vries_, Jun 26 2021