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A238689 Table read by rows: first row is {1}; for n >1, T(n, k) is the k-th largest prime factor of n (repeated prime factors are counted repeatedly).

%I A238689 #13 Sep 16 2016 02:44:01
%S A238689 1,2,3,2,2,5,3,2,7,2,2,2,3,3,5,2,11,3,2,2,13,7,2,5,3,2,2,2,2,17,3,3,2,
%T A238689 19,5,2,2,7,3,11,2,23,3,2,2,2,5,5,13,2,3,3,3,7,2,2,29,5,3,2,31,2,2,2,
%U A238689 2,2,11,3,17,2,7,5,3,3,2,2,37,19,2,13,3,5,2,2,2
%N A238689 Table read by rows: first row is {1}; for n >1, T(n, k) is the k-th largest prime factor of n (repeated prime factors are counted repeatedly).
%C A238689 n-th row has length 1 if n = 1, A001222(n) if n > 1.
%H A238689 Peter Kagey, <a href="/A238689/b238689.txt">Table of n, a(n) for n = 1..10000</a>
%F A238689 Row n is row n of A027746 in reverse order.
%e A238689 Table begins:
%e A238689 1;
%e A238689 2;
%e A238689 3;
%e A238689 2,2;
%e A238689 5;
%e A238689 3,2;
%e A238689 7;
%e A238689 2,2,2;
%e A238689 3,3;
%e A238689 5,2;
%e A238689 ...
%o A238689 (Haskell)
%o A238689 a238689_row 1 = [1]
%o A238689 a238689_row n = a n [] a000040_list where
%o A238689   a m factors ps@(p:ps')
%o A238689     | m == 1         = factors
%o A238689     | m `mod` p == 0 = a (m `div` p) (p : factors) ps
%o A238689     | otherwise      = a m           factors       ps'
%o A238689 a _ _ [] = [] -- _Peter Kagey_, Sep 15 2016
%Y A238689 First column is A006530; numbers along right boundary form A020639.
%Y A238689 A001414 gives row sums (for n > 1).
%Y A238689 Cf. A027746, A238690.
%K A238689 nonn,tabf
%O A238689 1,2
%A A238689 _Matthew Vandermast_, Apr 28 2014