cp's OEIS Frontend

A159081 Let d be the largest element of A008578 which divides n, then a(n) is the position of d in A008578.

%I A159081 #5 Mar 14 2015 11:53:00
%S A159081 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,
%T A159081 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,
%U A159081 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
%N A159081 Let d be the largest element of A008578 which divides n, then a(n) is the position of d in A008578.
%C A159081 Let p be the largest prime factor of n; if p = prime(k) then set a(n) = k + 1. a(n) = A061395(n) + 1.
%F A159081 a(n) = A049084(A006530(n)) + 1. A008578(a(n)) = A006530(n);
%e A159081 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.
%Y A159081 Cf.: A061395, A049084, A006530, A008578.
%K A159081 nonn,easy
%O A159081 1,2
%A A159081 _Jaroslav Krizek_, Apr 05 2009
%E A159081 Edited by _R. J. Mathar_, Apr 06 2009
%E A159081 Correction for change of offset in A158611 and A008578 in Aug 2009 _Jaroslav Krizek_, Jan 27 2010