A053047 EulerPhi is iterated with initial value n!; a(n) = first (maximal) power of 2 arising during iteration.

1, 2, 2, 8, 32, 64, 128, 1024, 1024, 8192, 65536, 262144, 1048576, 4194304, 16777216, 268435456, 4294967296, 8589934592, 17179869184, 274877906944, 549755813888, 8796093022208, 140737488355328, 1125899906842624

Offset

1,2

Links

Table of n, a(n) for n=1..24.

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}. The first power of 2 is the 6th term, arising after 5 iterations of phi; its value is 8192.

Crossrefs

Cf. A000010, A000142, A048855, A053038.

Sequence in context: A276657 A079895 A351512 * A076143 A226585 A057132

Adjacent sequences: A053044 A053045 A053046 * A053048 A053049 A053050

Keyword

nonn

Author

Labos Elemer, Feb 25 2000

Status

approved