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 A066924 #16 Nov 25 2023 14:29:20 %S A066924 1,4,9,36,345,6489,88473 %N A066924 Nonprime numbers n such that the GCD of n and the Chowla's function of n (A048050) is >= n/3. %C A066924 No more terms below 10^9. - _Amiram Eldar_, Aug 28 2019 %t A066924 Select[ Range[ 10^7 ], GCD[ #, DivisorSigma[ 1, # ] - # - 1 ] >= #/3 && !PrimeQ[ # ] & ] %o A066924 (PARI) f(n) = if(n>1, sigma(n)-n-1, 0); \\ A048050 %o A066924 isok(n) = !isprime(n) && gcd(n, f(n)) >= n/3; \\ _Michel Marcus_, Aug 28 2019 [Corrected by _Sean A. Irvine_, Nov 25 2023] %Y A066924 Cf. A048050, A074844. %K A066924 nonn,more %O A066924 1,2 %A A066924 _Robert G. Wilson v_, Jan 23 2002 %E A066924 Name clarified by _Sean A. Irvine_, Nov 25 2023