A107647 Euler's totient function applied to tribonacci numbers.

1, 1, 1, 2, 6, 12, 8, 20, 54, 148, 136, 144, 612, 1200, 1344, 2448, 10506, 16848, 13824, 22000, 83232, 148716, 205368, 377736, 920160, 1694088, 1880304, 3290112, 14839968, 22472640, 17805312, 42407136, 117876096, 327661128, 178588800, 561863168, 1604383200

Offset: 2

Author

Roger L. Bagula, Jun 09 2005

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 2..365

Crossrefs

Cf. A000010, A000073, A065449, A197218, A272040.

Programs

Mathematica

F[1] = 0; F[2] = 1; F[3] = 1; F[n__] := F[n] = F[n - 1] + F[n - 2] + F[n - 3]; Table[EulerPhi[F[n]], {n, 2, 50}]

Formula

a(n) = A000010(A000073(n)). - Amiram Eldar, Mar 02 2020

Extensions

First term 0 removed and offset corrected by Amiram Eldar, Mar 02 2020