A294926 Number of proper divisors of n that are deficient (A005100).

0, 1, 1, 2, 1, 3, 1, 3, 2, 3, 1, 4, 1, 3, 3, 4, 1, 4, 1, 5, 3, 3, 1, 5, 2, 3, 3, 5, 1, 6, 1, 5, 3, 3, 3, 5, 1, 3, 3, 6, 1, 6, 1, 5, 5, 3, 1, 6, 2, 5, 3, 5, 1, 5, 3, 6, 3, 3, 1, 7, 1, 3, 5, 6, 3, 6, 1, 5, 3, 7, 1, 6, 1, 3, 5, 5, 3, 6, 1, 7, 4, 3, 1, 7, 3, 3, 3, 7, 1, 8, 3, 5, 3, 3, 3, 7, 1, 5, 5, 7, 1, 6, 1, 7, 7

Offset: 1

Author

Antti Karttunen, Nov 14 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A032741, A080226, A294886, A294927, A294928, A294929, A294934.

Programs

Mathematica

a[n_] := DivisorSum[n, 1 &, # < n && DivisorSigma[1, #] < 2*# &]; Array[a, 100] (* Amiram Eldar, Mar 14 2024 *)

PARI

A294926(n) = sumdiv(n, d, (dAntti Karttunen, Nov 14 2017

Formula

a(n) = Sum_{d|n, dA294934(d).

a(n) = A080226(n) - A294934(n).

a(n) + A294927(n) = A032741(n).