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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).
10
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, 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, 2, 2, 11, 3, 17, 2, 7, 5, 3, 3, 2, 2, 37, 19, 2, 13, 3, 5, 2, 2, 2
OFFSET
1,2
COMMENTS
n-th row has length 1 if n = 1, A001222(n) if n > 1.
FORMULA
Row n is row n of A027746 in reverse order.
EXAMPLE
Table begins:
1;
2;
3;
2,2;
5;
3,2;
7;
2,2,2;
3,3;
5,2;
...
PROG
(Haskell)
a238689_row 1 = [1]
a238689_row n = a n [] a000040_list where
a m factors ps@(p:ps')
| m == 1 = factors
| m `mod` p == 0 = a (m `div` p) (p : factors) ps
| otherwise = a m factors ps'
a _ _ [] = [] -- Peter Kagey, Sep 15 2016
CROSSREFS
First column is A006530; numbers along right boundary form A020639.
A001414 gives row sums (for n > 1).
Sequence in context: A307746 A348477 A240230 * A166454 A283239 A318177
KEYWORD
nonn,tabf
AUTHOR
Matthew Vandermast, Apr 28 2014
STATUS
approved