A306897 a(n) = A306896(n)/6.

0, 1, 1, 4, 5, 14, 21, 48, 87, 180, 341, 704, 1365, 2758, 5475, 10976, 21845, 43806, 87381, 174960, 349573, 699402, 1398101, 2797008, 5592425, 11186188, 22369797, 44742040, 89478485, 178962840, 357913941, 715838912, 1431656457, 2863333392, 5726623175, 11453291400, 22906492245, 45813071890

Offset: 1

Author

Michael De Vlieger and N. J. A. Sloane, Mar 15 2019

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..3324
• Silvana Ramaj, New Results on Cyclic Compositions and Multicompositions, Master's Thesis, Georgia Southern Univ., 2021. See p. 48.

Crossrefs

Cf. A306896.

Programs

Mathematica

Table[DivisorSum[n, (2^# + 2 (-1)^#) EulerPhi[n/#] &]/6, {n, 38}] (* Michael De Vlieger, Mar 18 2019 *)

PARI

a(n) = sumdiv(n, d, (2^d + 2*(-1)^d)*eulerphi(n/d))/6; \\ Michel Marcus, Mar 16 2019