A053025 Number of iterations of A000005 required to reach 2 when started at n!.

1, 1, 4, 5, 4, 6, 7, 7, 7, 5, 7, 7, 7, 7, 7, 6, 7, 7, 7, 7, 7, 8, 7, 7, 7, 7, 6, 6, 8, 6, 7, 6, 7, 8, 6, 8, 7, 5, 7, 6, 8, 6, 6, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 7, 8, 7, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 7, 8, 8, 8, 7, 8, 8, 7, 8, 8, 8, 8, 8

Offset

1,3

Links

Table of n, a(n) for n=1..105.

Formula

a(n) = A036459(A000142(n)) = A036459(n!).

Example

For n=108, a(108)=9 because the sequence of iterates is {108!,798687560466432000,7920,60,12,6,4,3,2}, length=9.

Crossrefs

Cf. A000005, A036459, A000142.

Sequence in context: A248624 A363195 A085428 * A010664 A074967 A021877

Adjacent sequences: A053022 A053023 A053024 * A053026 A053027 A053028

Keyword

nonn

Author

Labos Elemer, Feb 24 2000

Status

approved