A053046 EulerPhi is iterated with initial value n!; a(n) = number of terms that are not powers of 2 among the iterates.

0, 0, 1, 1, 1, 2, 3, 3, 5, 5, 5, 6, 7, 8, 9, 9, 9, 11, 13, 13, 15, 15, 15, 16, 16, 17, 20, 21, 22, 23, 24, 24, 25, 25, 26, 28, 30, 32, 34, 34, 34, 36, 38, 38, 40, 40, 40, 41, 43, 43, 44, 45, 46, 49, 49, 50, 53, 54, 55, 56, 57, 58, 61, 61, 62, 63, 64, 64, 65, 66, 67, 69, 71, 73, 74

Offset

1,6

Comments

Non-powers of 2 arise at the beginning of iteration chains without interruption. Analogous to A053036.

Links

Table of n, a(n) for n=1..75.

Formula

a(n) = 1+A053044(n)-A053045(n). - R. J. Mathar, Jan 09 2017

Example

For n=10, initial value = 3628800; the iteration chain is {3628800, 829440, 221184, 73728, 24576, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1}. Its length is 19 and the 5 initial values are not powers of 2: 10!, ..., 24576. Thus a(10)=5.

Crossrefs

Cf. A000010, A000142, A048855, A053036.

Sequence in context: A083662 A256405 A130149 * A261179 A066658 A005145

Adjacent sequences: A053043 A053044 A053045 * A053047 A053048 A053049

Keyword

nonn

Author

Labos Elemer, Feb 25 2000

Status

approved