A279914 a(n) = sigma(n) + phi(n) - mu(n).

1, 5, 7, 9, 11, 13, 15, 19, 19, 21, 23, 32, 27, 29, 31, 39, 35, 45, 39, 50, 43, 45, 47, 68, 51, 53, 58, 68, 59, 81, 63, 79, 67, 69, 71, 103, 75, 77, 79, 106, 83, 109, 87, 104, 102, 93, 95, 140, 99, 113, 103, 122, 107, 138, 111, 144, 115, 117, 119, 184, 123

Offset

1,2

Comments

If n is prime or semiprime, then a(n) = 2n+1.

Links

Table of n, a(n) for n=1..61.

Formula

a(n) = A000203(n) + A000010(n) - A008683(n).

Maple

with(numtheory): a:=n->sigma(n)+phi(n)-mobius(n): seq(a(n), n=1..100);

Mathematica

Table[DivisorSigma[1, n] + EulerPhi[n] - MoebiusMu[n], {n, 100}]

Prog

(PARI) a(n) = {my(f = factor(n)); sigma(f) + eulerphi(f) - moebius(f); } \\ Amiram Eldar, Nov 14 2024

Crossrefs

Cf. A000010, A000203, A008683.

Sequence in context: A329391 A108144 A241835 * A123910 A024886 A083249

Adjacent sequences: A279911 A279912 A279913 * A279915 A279916 A279917

Keyword

nonn,easy

Author

Wesley Ivan Hurt, Dec 22 2016

Status

approved