A344672 a(n) = Sum_{primes p <=n} phi(floor(n/p)).

0, 1, 2, 2, 3, 4, 5, 5, 6, 8, 9, 7, 8, 12, 15, 13, 14, 14, 15, 13, 18, 24, 25, 17, 19, 27, 29, 23, 24, 22, 23, 23, 30, 38, 44, 28, 29, 41, 50, 38, 39, 35, 36, 34, 38, 50, 51, 37, 41, 51, 60, 52, 53, 49, 57, 49, 62, 78, 79, 43, 44, 66, 72, 58, 68, 68, 69, 65, 78, 78

Offset

1,3

Links

Michel Marcus, Table of n, a(n) for n = 1..10000

Mathematica

a[n_] := Plus @@ EulerPhi[Floor[n/Select[Range[n], PrimeQ]]]; Array[a, 100] (* Amiram Eldar, Jul 05 2021 *)

Prog

(PARI) a(n) = my(s=0); forprime(p=2, n, s+=eulerphi(n\p)); s;

Crossrefs

Cf. A000010, A013939 (with k instead of phi(k)), A346111 (with sigma instead).

Cf. A317625.

Sequence in context: A241730 A011884 A029070 * A360141 A354945 A112341

Adjacent sequences: A344669 A344670 A344671 * A344673 A344674 A344675

Keyword

nonn

Author

Michel Marcus, Jul 05 2021

Status

approved