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A055767
Index (or subscript) of the largest primorial (A002110(k)) which divides EulerPhi of the n-th primorial (A005867(n)).
0
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
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
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 12 2000
EXTENSIONS
Data corrected by Sean A. Irvine, Apr 05 2022
STATUS
approved