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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
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.
Sequence in context: A333145 A335449 A318464 * A008647 A036475 A330746
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified March 29 08:13 EDT 2024. Contains 371265 sequences. (Running on oeis4.)