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 A137944 #17 Apr 18 2025 09:56:56 %S A137944 2,3,4,5,7,8,9,11,13,16,17,19,23,25,27,29,31,32,36,37,41,43,47,49,53, %T A137944 59,61,64,67,71,73,79,81,83,89,97,100,101,103,107,109,113,120,121,125, %U A137944 127,128,131,137,139,144,149,151,157,163,167,168,169,173,179,181,191,193 %N A137944 Numbers such that the number of composite divisors is a multiple of the number of prime divisors. %H A137944 Reinhard Zumkeller, <a href="/A137944/b137944.txt">Table of n, a(n) for n = 1..10000</a> %H A137944 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DivisorFunction.html">Divisor Function</a>. %F A137944 A055212(a(n)) mod A001221(a(n)) = 0. %t A137944 aQ[n_] := Divisible[DivisorSigma[0, n] - 1, PrimeNu[n]]; Select[Range[2, 193], aQ] (* _Amiram Eldar_, Aug 31 2019 *) %o A137944 (PARI) isok(k) = if(k == 1, 0, my(f = factor(k)); !((numdiv(f)-1) % omega(f))); \\ _Amiram Eldar_, Apr 18 2025 %Y A137944 Cf. A001221, A055212. %Y A137944 Disjoint union of A000961 and A137945. %K A137944 nonn %O A137944 1,1 %A A137944 _Reinhard Zumkeller_, Feb 24 2008