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A107647 Euler's totient function applied to tribonacci numbers. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

LINKS

Amiram Eldar, Table of n, a(n) for n = 2..303

FORMULA

F(n) = F(n-1) + F(n-2) + F(n-3); a(n) = phi(F(n)).

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

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}]

CROSSREFS

Cf. A000010, A000073, A065449.

Sequence in context: A113540 A111658 A105692 * A210842 A245777 A245785

Adjacent sequences:  A107644 A107645 A107646 * A107648 A107649 A107650

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Jun 09 2005

EXTENSIONS

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

STATUS

approved

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Last modified August 7 23:38 EDT 2020. Contains 336279 sequences. (Running on oeis4.)