A348977 a(n) = gcd(sigma(n), A332993(n)).

1, 3, 4, 7, 6, 2, 8, 15, 13, 2, 12, 2, 14, 2, 3, 31, 18, 1, 20, 6, 1, 2, 24, 2, 31, 2, 40, 2, 30, 3, 32, 63, 3, 2, 1, 1, 38, 2, 1, 2, 42, 1, 44, 6, 6, 2, 48, 2, 57, 3, 3, 2, 54, 2, 1, 2, 1, 2, 60, 3, 62, 2, 4, 127, 1, 3, 68, 6, 3, 1, 72, 1, 74, 2, 2, 2, 1, 1, 80, 6, 121, 2, 84, 1, 1, 2, 3, 2, 90, 78, 7, 6, 1, 2, 5

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences related to sigma(n)

Formula

a(n) = gcd(A000203(n), A332993(n)).

a(n) = gcd(A000203(n), A333783(n)) = gcd(A332993(n), A333783(n)).

a(n) = A332993(n) / A348978(n) = A000203(n) / A348979(n).

Mathematica

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

Prog

(PARI)
A332993(n) = if(1==n, n, n + A332993(n/vecmin(factor(n)[, 1])));
A348977(n) = gcd(sigma(n), A332993(n));

Crossrefs

Cf. A000203, A332993, A333783, A348978, A348979.

Cf. also A348987.

Sequence in context: A105853 A277216 A323394 * A017665 A248789 A105852

Adjacent sequences: A348974 A348975 A348976 * A348978 A348979 A348980

Keyword

nonn

Author

Antti Karttunen, Nov 06 2021

Status

approved