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A063928 Largest nonprime proper divisor of n (with a(1)=1). 3
1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 6, 1, 1, 1, 8, 1, 9, 1, 10, 1, 1, 1, 12, 1, 1, 9, 14, 1, 15, 1, 16, 1, 1, 1, 18, 1, 1, 1, 20, 1, 21, 1, 22, 15, 1, 1, 24, 1, 25, 1, 26, 1, 27, 1, 28, 1, 1, 1, 30, 1, 1, 21, 32, 1, 33, 1, 34, 1, 35, 1, 36, 1, 1, 25, 38, 1, 39, 1, 40, 27, 1, 1, 42, 1, 1, 1, 44, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

COMMENTS

a(m)*a(n)<=a(m*n); a(m)*a(n)=a(m*n) iff m and n are prime or = 1. - Reinhard Zumkeller, Apr 11 2008

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..1000

PROG

(PARI) { for (n=1, 1000, if (n==1, a=1, d=divisors(n); m=length(d); until (!isprime(a), m--; a=d[m])); write("b063928.txt", n, " ", a) ) } [From Harry J. Smith, Sep 02 2009]

CROSSREFS

a(n)=1 if n is 1, prime (A000040), or the product of two primes (A001358), i.e. if n is in A037143, otherwise, with n in A033942, a(n)=A032742(n). Cf. A006530.

Sequence in context: A008833 A162400 A179054 * A182665 A131299 A073937

Adjacent sequences:  A063925 A063926 A063927 * A063929 A063930 A063931

KEYWORD

nonn

AUTHOR

Henry Bottomley, Aug 15 2001

STATUS

approved

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Last modified December 13 00:17 EST 2017. Contains 295954 sequences.