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 A079879 Median prime factor: a(1)=1 and for n>1: least prime p such that not more than floor(Omega(n)/2) prime factors are greater than p; Omega(n) is the total number of prime factors of n (A001222). 4
 1, 2, 3, 2, 5, 2, 7, 2, 3, 2, 11, 2, 13, 2, 3, 2, 17, 3, 19, 2, 3, 2, 23, 2, 5, 2, 3, 2, 29, 3, 31, 2, 3, 2, 5, 2, 37, 2, 3, 2, 41, 3, 43, 2, 3, 2, 47, 2, 7, 5, 3, 2, 53, 3, 5, 2, 3, 2, 59, 2, 61, 2, 3, 2, 5, 3, 67, 2, 3, 5, 71, 2, 73, 2, 5, 2, 7, 3, 79, 2, 3, 2, 83, 2, 5, 2, 3, 2, 89, 3, 7, 2, 3, 2, 5, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A020639(n)<= a(n)<=A006530(n); a(m)=A020639(m)=A006530(m) iff m is a prime power (A000961). LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE a(30)=a(2*3*5)=3; a(60)=a(2*2*3*5)=2; a(72)=a(2*2*2*3*3)=2; a(90)=a(2*3*3*5)=3; a(108)=a(2*2*3*3*3)=3; a(144)=a(2*2*2*2*3*3)=2; a(216)=a(2*2*2*3*3*3)=2. MAPLE f:= proc(n) local F, F2, m, i;     F:= sort(ifactors(n)[2], (i, j) -> i[1]=F2[-1] then return F[i][1] fi     od end proc: 1, seq(f(n), n=2..100); # Robert Israel, Aug 25 2015 MATHEMATICA f[n_] := Block[{p = Flatten[Table[#1, {#2}] & @@@ FactorInteger@ n], len}, len = Length@ p; If[OddQ@ len, p[[1 + Floor[len/2]]], p[[len/2]]]]; {1}~Join~Table[f@ n, {n, 2, 96}] (* Michael De Vlieger, Aug 25 2015 *) CROSSREFS Cf. A033676, A001222, A079880, A079881. Sequence in context: A020639 A092067 A214606 * A071889 A091963 A067695 Adjacent sequences:  A079876 A079877 A079878 * A079880 A079881 A079882 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jan 13 2003 EXTENSIONS Typo fixed by Franklin T. Adams-Watters, Jul 10 2012 STATUS approved

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Last modified December 13 08:08 EST 2018. Contains 318082 sequences. (Running on oeis4.)