cp's OEIS Frontend

A078899 Number of times the greatest prime factor of n is the greatest prime factor for numbers <=n; a(1)=1.

%I A078899 #12 Jun 09 2018 04:20:58
%S A078899 1,1,1,2,1,2,1,3,3,2,1,4,1,2,3,4,1,5,1,4,3,2,1,6,5,2,7,4,1,6,1,5,3,2,
%T A078899 5,8,1,2,3,7,1,6,1,4,8,2,1,9,7,9,3,4,1,10,5,8,3,2,1,10,1,2,9,6,5,6,1,
%U A078899 4,3,10,1,11,1,2,11,4,7,6,1,12,12,2,1,11,5,2,3,8,1,13,7,4,3,2,5,13,1,12,9
%N A078899 Number of times the greatest prime factor of n is the greatest prime factor for numbers <=n; a(1)=1.
%C A078899 For n>1: a(n)=1 iff n is prime;
%C A078899 a(n) = n/p for n<=p*(p+1) and p = greatest prime factor of n.
%H A078899 Alois P. Heinz, <a href="/A078899/b078899.txt">Table of n, a(n) for n = 1..20000</a>
%F A078899 Ordinal transform of A006530 (Gpf). - _Franklin T. Adams-Watters_, Aug 28 2006
%p A078899 p:= proc() 0 end:
%p A078899 a:= proc(n) option remember; local t;
%p A078899       t:= max(numtheory[factorset](n)[]);
%p A078899       p(t):= p(t)+1
%p A078899     end:
%p A078899 seq(a(n), n=1..100);  # _Alois P. Heinz_, Oct 09 2015
%t A078899 p[_] = 0; a[1] = 1;
%t A078899 a[n_] := a[n] = Module[{t}, t = FactorInteger[n][[-1, 1]]; p[t] = p[t]+1];
%t A078899 Array[a, 100] (* _Jean-François Alcover_, Jun 09 2018, after _Alois P. Heinz_ *)
%Y A078899 Cf. A006530, A078898, A078897.
%K A078899 nonn,look
%O A078899 1,4
%A A078899 _Reinhard Zumkeller_, Dec 12 2002