A228807 a(n) = phi( a(n-1) + a(n-2) + 1) with a(0) = 0 and a(1) = 1.

0, 1, 1, 2, 2, 4, 6, 10, 16, 18, 24, 42, 66, 108, 120, 228, 348, 576, 720, 1296, 2016, 3312, 5256, 7200, 12456, 17860, 25200, 40256, 37368, 39600, 72900, 112500, 185400, 282204, 364800, 517600, 805392, 1133988, 1939380, 2788176, 4727556, 6819120

Offset

0,4

Comments

Difference between A000045 & A228807: 0, 0, 0, 0, 1, 1, 2, 3, 5, 16, 31, 47, 78, 125, 257, 382, 639, 1021, 1864, 2885, 4749, 7634, ... .

Links

Mihai Caragiu and Robert G. Wilson v, Table of n, a(n) for n = 0..500

Mihai Caragiu, Mathematical Trips.

Mihai Caragiu and Ashley Risch, An Euler-Fibonacci Sequence, Far East Journal of Mathematical Sciences 52 (1), 1 - 7 (May 2011)

Formula

a(n) = phi( a(n-1) + a(n-2) + 1) with a(0) = 0 & a(1) = 1.

Mathematica

a[0] = 0; a[1] = 1; a[n_] := a[n] = EulerPhi[a[n - 1] + a[n - 2] + 1]; Array[a, 50, 0]
RecurrenceTable[{a[0]==0, a[1]==1, a[n]==EulerPhi[a[n-1]+a[n-2]+1]}, a, {n, 50}] (* Harvey P. Dale, Feb 16 2014 *)

Crossrefs

Cf. A000010, A000045.

Sequence in context: A192682 A050194 A288006 * A262258 A293633 A006355

Adjacent sequences: A228804 A228805 A228806 * A228808 A228809 A228810

Keyword

nonn

Author

Mihai Caragiu and Robert G. Wilson v, Sep 04 2013

Status

approved