cp's OEIS Frontend

A330754 Number of values of k, 1 <= k <= n, with A330691(k) = A330691(n), where A330691(n) = gcd(n, A309639(n)).

%I A330754 #12 Jan 11 2022 08:28:40
%S A330754 1,1,1,1,1,2,1,1,1,2,1,2,1,2,3,1,1,2,1,4,3,2,1,4,1,2,1,3,1,5,1,1,3,2,
%T A330754 4,3,1,2,3,2,1,5,1,4,4,2,1,2,1,2,3,4,1,2,5,3,3,2,1,6,1,2,5,1,5,6,1,4,
%U A330754 6,5,1,6,1,2,3,4,7,6,1,3,1,2,1,7,5,2,3,8,1,7,7,3,3,2,5,2,1,2,9,4,1,6,1,8,8
%N A330754 Number of values of k, 1 <= k <= n, with A330691(k) = A330691(n), where A330691(n) = gcd(n, A309639(n)).
%C A330754 Ordinal transform of A330691.
%H A330754 Antti Karttunen, <a href="/A330754/b330754.txt">Table of n, a(n) for n = 1..65537</a>
%t A330754 A309639[n_] := For[k = 1, True, k++, If[Divisible[Denominator[ HarmonicNumber[k]], n], Return[k]]];
%t A330754 A330691[n_] := GCD[n, A309639[n]];
%t A330754 Module[{b}, b[_] = 0;
%t A330754 a[n_] := With[{t = A330691[n]}, b[t] = b[t] + 1]];
%t A330754 Array[a, 105] (* _Jean-François Alcover_, Jan 11 2022 *)
%o A330754 (PARI)
%o A330754 A330691(n) = gcd(n, A309639(n));
%o A330754 ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
%o A330754 v330754 = ordinal_transform(vector(up_to, n, A330691(n)));
%o A330754 A330754(n) = v330754[n];
%Y A330754 Cf. A309639, A330691, A330753.
%K A330754 nonn
%O A330754 1,6
%A A330754 _Antti Karttunen_, Dec 30 2019