A060609 Repeatedly apply Euler phi to n-th prime; a(n) = highest power of 2 that is seen.

2, 2, 4, 2, 4, 4, 16, 2, 4, 4, 8, 4, 16, 4, 4, 8, 4, 16, 8, 8, 8, 8, 16, 16, 32, 16, 32, 8, 4, 16, 4, 16, 64, 8, 8, 16, 16, 2, 16, 8, 16, 16, 8, 64, 8, 16, 16, 8, 16, 8, 16, 32, 64, 16, 256, 16, 16, 8, 16, 32, 8, 16, 32, 32, 32, 16, 32, 32, 8, 16, 64, 16, 32, 32, 4, 8, 64, 32, 64, 128

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A049116(A000040(n)).

Example

n=100,p(100)=541, Phi-iteration chain is {541,540,144,48,16,8,4,2,1} with 9 terms. The largest power of 2 is the 5th term=16=a(100).

Crossrefs

Cf. A000040, A000010, A049108, A049113, A049116, A003434.

Sequence in context: A116467 A079314 A323381 * A330882 A205138 A233763

Adjacent sequences: A060606 A060607 A060608 * A060610 A060611 A060612

Keyword

easy,nonn

Author

Labos Elemer, Apr 13 2001

Status

approved