A152772 -id:A152772 - cp's OEIS frontend

A152771 a(n) = sigma(n) - 2*d(n) + 1.

0, 0, 1, 2, 3, 5, 5, 8, 8, 11, 9, 17, 11, 17, 17, 22, 15, 28, 17, 31, 25, 29, 21, 45, 26, 35, 33, 45, 27, 57, 29, 52, 41, 47, 41, 74, 35, 53, 49, 75, 39, 81, 41, 73, 67, 65, 45, 105, 52, 82, 65, 87, 51, 105, 65, 105, 73, 83, 57, 145

Offset: 1

Omar E. Pol, Dec 14 2008

Ivan Neretin, Table of n, a(n) for n = 1..10000

Cf. A000005, A000203, A152770, A152772.

Table[DivisorSigma[1, n] - 2 DivisorSigma[0, n] + 1, {n, 60}] (* Ivan Neretin, Sep 30 2017 *)

a(n) = sigma(n) - 2*numdiv(n) + 1; \\ Michel Marcus, Sep 30 2017

a(n) = A000203(n) - 2*A000005(n) + 1 = A000203(n) - A114003(n) = A088580(n) - A062011(n). - Omar E. Pol, Sep 30 2017

G.f.: Sum_{k>=1} x^(3*k) / (1 - x^k)^2. - Ilya Gutkovskiy, Apr 24 2021

A152864 Deficiency of n, plus the number of proper divisors of n: a(n) = 2n - sigma(n) + d(n) - 1.

Original entry on oeis.org

1, 2, 3, 3, 5, 3, 7, 4, 7, 5, 11, 1, 13, 7, 9, 5, 17, 2, 19, 3, 13, 11, 23, -5, 21, 13, 17, 5, 29, -5, 31, 6, 21, 17, 25, -11, 37, 19, 25, -3, 41, -5, 43, 9, 17, 23, 47, -19, 43, 12, 33, 11, 53, -5, 41, -1, 37, 29, 59, -37, 61, 31

Offset: 1

Omar E. Pol, Dec 14 2008

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A000005, A000203, A005843, A032741, A033879, A152770, A152771, A152772.

a[n_] := 2*n - Differences[DivisorSigma[{0, 1}, n]][[1]] - 1; Array[a, 100] (* Amiram Eldar, Apr 07 2024 *)

a(n) = 2*n - sigma(n) + numdiv(n) - 1; \\ Amiram Eldar, Apr 07 2024

a(n) = A005843(n)-A000203(n)+A000005(n)-1 = A033879(n)+A032741(n).

cp's OEIS Frontend

A152771 a(n) = sigma(n) - 2*d(n) + 1.

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica

PARI

Formula