A055767 Index (or subscript) of the largest primorial (A002110(k)) which divides EulerPhi of the n-th primorial (A005867(n)).

0, 1, 1, 2, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16

Offset

1,4

Links

Table of n, a(n) for n=1..76.

Formula

Max{q primorials: q divides A000010(A002110(n))}.

Example

n=52: prime factors of phi(A002110(52)) = phi(2*3*5*7*...*233*239) are {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 37, 41, 43, 53, 83, 89, 113} in which the length of the initial prime continuous part is 10, thus a(52)=10.

Crossrefs

Cf. A000010, A002110, A005867.

Sequence in context: A052288 A280455 A284725 * A029110 A249420 A103959

Adjacent sequences: A055764 A055765 A055766 * A055768 A055769 A055770

Keyword

nonn

Author

Labos Elemer, Jul 12 2000

Extensions

Data corrected by Sean A. Irvine, Apr 05 2022

Status

approved