A062804 phi(n) - floor(n^(1/3))*tau(n) = 0.

1, 3, 9, 15, 56, 102, 198, 228, 234, 280, 312, 528, 672, 756, 1050, 1320

Offset

1,2

Comments

See comment to A062516.

Links

Table of n, a(n) for n=1..16.

Example

For m=1320, Phi[m]-k[m]*Tau[m]=320-10*32=0. 16 terms below 100000 [and most likely at all]. phi(n)-Floor[n^(1/3)]*Tau[n] becomes positive for large n. At n=2520 seems last time negative.

Mathematica

Flatten[Position[Table[EulerPhi[w]-Floor[w^(1/3)//N]*DivisorSigma[0, w], {w, 1, 100000}], 0]]

Prog

(PARI) isok(n) = eulerphi(n) - sqrtnint(n, 3)*numdiv(n) == 0; \\ Michel Marcus, Aug 24 2019

Crossrefs

Cf. A062516, A000005, A000010.

Sequence in context: A329420 A120403 A247967 * A110960 A192165 A050869

Adjacent sequences: A062801 A062802 A062803 * A062805 A062806 A062807

Keyword

fini,nonn

Author

Labos Elemer, Jul 20 2001

Status

approved