A107797 a(n) = phi(Padovan(n+4)).

1, 1, 1, 1, 1, 2, 2, 4, 6, 6, 4, 8, 12, 12, 36, 42, 48, 42, 36, 150, 80, 208, 216, 240, 240, 256, 1012, 712, 1620, 2148, 3328, 1008, 2772, 7560, 4640, 9036, 11988, 23832, 10512, 20896, 37968, 35960, 88380, 122004, 72000, 77472, 149712, 271824, 168960, 451440

Offset

1,6

Links

Amiram Eldar, Table of n, a(n) for n = 1..748 [Terms a(85), a(129), a(470), a(667) corrected by Georg Fischer, Feb 28 2026]

Formula

a(n) = A000010(A000931(n+4)). - R. J. Mathar, Sep 11 2011

a(n) = A000010(A134816(n)). - Alois P. Heinz, Feb 28 2026

Maple

A107797 := proc(n)
        numtheory[phi](A000931(n+4)) ;
end proc:
seq(A107797(n), n=1..50) ; # R. J. Mathar, Sep 11 2011
# Alternative:
a:= n-> numtheory[phi]((<<0|1|0>, <0|0|1>, <1|1|0>>^n)[3, 2]):
seq(a(n), n=1..50); # Alois P. Heinz, Feb 28 2026

Mathematica

(* Method one *) M = {{0, 1, 0}, {0, 0, 1}, {1, 1, 0}}; v[1] = {0, 1, 1}; v[n_] := v[n] = M.v[n - 1]; a = Table[EulerPhi[v[n][[1]]], {n, 2, 50}]
(* Method two *) F[1] = 0; F[2] = 1; F[3] = 1; F[n_] := F[n] = F[n - 2] + F[n - 3]; a = Table[EulerPhi[F[n]], {n, 2, 50}]

Crossrefs

Cf. A000010, A000931, A134816.

Sequence in context: A347797 A351746 A118960 * A316788 A038759 A045999

Adjacent sequences: A107794 A107795 A107796 * A107798 A107799 A107800

Keyword

nonn

Author

Roger L. Bagula, Jun 11 2005

Extensions

Offset changed to 1 and a(0) removed by Amiram Eldar, Nov 10 2024

Status

approved