A348989 Denominator of ratio A332994(n) / sigma(n).

1, 1, 1, 1, 1, 4, 1, 1, 1, 18, 1, 28, 1, 24, 24, 1, 1, 13, 1, 14, 32, 36, 1, 20, 1, 42, 1, 8, 1, 24, 1, 1, 48, 54, 48, 91, 1, 60, 56, 18, 1, 32, 1, 28, 39, 72, 1, 124, 1, 31, 72, 98, 1, 40, 72, 120, 80, 90, 1, 168, 1, 96, 26, 1, 84, 48, 1, 42, 96, 144, 1, 65, 1, 114, 62, 140, 96, 56, 1, 62, 1, 126, 1, 224, 108, 132, 120

Offset

1,6

Comments

See comments in A348988.

Links

Table of n, a(n) for n=1..87.

Index entries for sequences related to sigma(n)

Formula

a(n) = A000203(n) / A348987(n) = A000203(n) / gcd(A000203(n), A332994(n)).

Mathematica

f[n_] := n/FactorInteger[n][[-1, 1]]; g[1] = 1; g[n_] := g[n] = n + g[f[n]]; a[n_] := Denominator[g[n]/DivisorSigma[1, n]]; Array[a, 100] (* Amiram Eldar, Nov 06 2021 *)

Prog

(PARI)
A332994(n) = if(1==n, n, n + A332994(n/vecmax(factor(n)[, 1])));
A348989(n) = { my(s=sigma(n)); (s/gcd(s, A332994(n))); };

Crossrefs

Cf. A000203, A332994, A333784, A348987, A348988 (numerators).

Cf. also A348978, A348979.

Sequence in context: A203639 A358319 A265679 * A362297 A354358 A112622

Adjacent sequences: A348986 A348987 A348988 * A348990 A348991 A348992

Keyword

nonn,frac

Author

Antti Karttunen, Nov 06 2021

Status

approved