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A159081 Let d be the largest element of A008578 which divides n, then a(n) is the position of d in A008578. 0
1, 2, 3, 2, 4, 3, 5, 2, 3, 4, 6, 3, 7, 5, 4, 2, 8, 3, 9, 4, 5, 6, 10, 3, 4, 7, 3, 5, 11, 4, 12, 2, 6, 8, 5, 3, 13, 9, 7, 4, 14, 5, 15, 6, 4, 10, 16, 3, 5, 4, 8, 7, 17, 3, 6, 5, 9, 11, 18, 4, 19, 12, 5, 2, 7, 6, 20, 8, 10, 5, 21, 3, 22, 13, 4, 9, 6, 7, 23, 4, 3, 14, 24, 5, 8, 15, 11, 6, 25, 4, 7, 10, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Let p be the largest prime factor of n; if p = prime(k) then set a(n) = k + 1. a(n) = A061395(n) + 1.

LINKS

Table of n, a(n) for n=1..93.

FORMULA

a(n) = A049084(A006530(n)) + 1. A008578(a(n)) = A006530(n);

EXAMPLE

For n=30, the largest element of the set {1,2,3,5} (1 and prime divisors of 30) is 5, and 5 is a(n)=4th term of A008578, the extended set of primes.

CROSSREFS

Cf.: A061395, A049084, A006530, A008578.

Sequence in context: A241054 A257907 A139094 * A141285 A286531 A317765

Adjacent sequences:  A159078 A159079 A159080 * A159082 A159083 A159084

KEYWORD

nonn,easy

AUTHOR

Jaroslav Krizek, Apr 05 2009

EXTENSIONS

Edited by R. J. Mathar, Apr 06 2009

Correction for change of offset in A158611 and A008578 in Aug 2009 Jaroslav Krizek, Jan 27 2010

STATUS

approved

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Last modified May 24 17:09 EDT 2019. Contains 323533 sequences. (Running on oeis4.)