A092790 a(n) = (n+1)*phi(n-1)/2.

2, 5, 6, 14, 8, 27, 20, 33, 24, 65, 28, 90, 48, 68, 72, 152, 60, 189, 88, 138, 120, 275, 104, 270, 168, 261, 180, 434, 128, 495, 272, 350, 288, 444, 228, 702, 360, 492, 336, 860, 264, 945, 460, 564, 528, 1127, 400, 1071, 520, 848, 648, 1430, 504, 1140, 696, 1062, 840, 1769

Offset: 3

Author

N. J. A. Sloane, Nov 04 2008

Keywords

• nonn
• easy

Comments

[The old entry with this sequence number was a duplicate of A082470.]

Prepending [0, 3] and setting offset = 0 the sequence becomes the row sums of A378068. - Peter Luschny, Dec 27 2024

a(n) is the sum of row n-1 of A078401. - Amiram Eldar, May 12 2025

Links

• Amiram Eldar, Table of n, a(n) for n = 3..10000
• Jeffrey Jaffe, Permutation numbers, Math. Mag., 49 (1976), 80-84.

Crossrefs

Cf. A000010 (phi), A078401, A378068.

Programs

Mathematica

Table[(n+1) EulerPhi[n-1]/2,{n,3,60}] (* Harvey P. Dale, Apr 22 2012 *)

PARI

a(n) = (n+1)*eulerphi(n-1)/2; \\ Michel Marcus, Sep 18 2017