A387718 Smallest divisor d of n such that n/d is deficient, i.e., sigma(n/d) < 2*(n/d).

1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 4, 1, 1, 1, 4, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 4, 1, 1, 1, 4, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 8, 1, 1, 1, 1, 1, 2, 1, 5, 1, 1, 1, 4, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 1, 2, 1

Offset

1,6

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Formula

a(n) = n / A387717(n).

a(n) >= A378660(n).

Prog

(PARI) A387718(n) = { fordiv(n, d, if(sigma(n/d)<2*(n/d), return(d))); (n); };

Crossrefs

Cf. A000203, A005100 (positions of 1's), A378660, A387717.

Sequence in context: A389900 A285337 A328457 * A340827 A360119 A033630

Adjacent sequences: A387715 A387716 A387717 * A387719 A387720 A387721

Keyword

nonn

Author

Antti Karttunen, Sep 11 2025

Status

approved