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A051265 Maximal value of prime divisors of numbers in reduced residue system for n. 5
0, 0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 1, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 1, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

The smallest number for which a(n)=k is the n-th Euclid number (A006862=A002110 + 1).

Largest value of A001221(k) for 1 <= k <= n such that gcd(k, n) = 1. - Michael De Vlieger, Aug 10 2017

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Z. Abel, E. Demaine, M. Demaine, H. Matsui and G. Rote, Common Developments of Several Different Orthogonal Boxes, CCCG 2011, Toronto ON, August 10-12, 2011.

FORMULA

a(n) << log n/log log n. - Charles R Greathouse IV, Aug 10 2017

EXAMPLE

For n=60 a(n)=1 since in RRS[ 60 ] only 1 and prime powers occur (see A051250).

MATHEMATICA

Table[Max@ Map[PrimeNu, Cases[Range[n - 1], k_ /; CoprimeQ[n, k]]] /. k_ /; ! IntegerQ@ k -> 0, {n, 105}] (* Michael De Vlieger, Aug 10 2017 *)

PROG

(PARI) a(n)=my(k=1, s); forprime(p=2, , if(n%p==0, next); k*=p; if(k>n, return(s)); s++) \\ Charles R Greathouse IV, Aug 10 2017

CROSSREFS

Records are A006862.

Cf. A001221, A002110, A051250, A051266, A051267, A051268.

Sequence in context: A333145 A335449 A318464 * A008647 A036475 A330746

Adjacent sequences:  A051262 A051263 A051264 * A051266 A051267 A051268

KEYWORD

nonn,easy

AUTHOR

Labos Elemer

STATUS

approved

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Last modified April 12 21:13 EDT 2021. Contains 342932 sequences. (Running on oeis4.)