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 A349634 #13 Dec 06 2021 03:05:43 %S A349634 1,2,3,4,5,3,7,8,9,5,11,2,13,7,15,16,17,9,19,10,21,11,23,4,25,13,27,7, %T A349634 29,15,31,32,33,17,35,6,37,19,39,20,41,21,43,22,9,23,47,8,49,25,51,13, %U A349634 53,27,55,14,57,29,59,5,61,31,63,64,65,33,67,34,23,35,71,4,73,37,75,19,77,39,79,40,81,41,83,7 %N A349634 Denominators of the Möbius transform of ratio A003961(n)/n. %C A349634 See comments in A349633. %H A349634 Antti Karttunen, <a href="/A349634/b349634.txt">Table of n, a(n) for n = 1..20000</a> %t A349634 f[p_, e_] := NextPrime[p]^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; a[n_] := Denominator @ DivisorSum[n, MoebiusMu[n/#] * s[#]/# &]; Array[a, 100] (* _Amiram Eldar_, Nov 28 2021 *) %o A349634 (PARI) %o A349634 A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961 %o A349634 A349634(n) = denominator(sumdiv(n,d,moebius(n/d)*(A003961(d)/d))); %Y A349634 Cf. A000010, A003961, A003972, A008683, A349633 (numerators). %Y A349634 Cf. also A349628. %K A349634 nonn,frac %O A349634 1,2 %A A349634 _Antti Karttunen_, Nov 28 2021