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A163870 Triangle read by rows: row n lists the nontrivial divisors of the n-th composite. 15
2, 2, 3, 2, 4, 3, 2, 5, 2, 3, 4, 6, 2, 7, 3, 5, 2, 4, 8, 2, 3, 6, 9, 2, 4, 5, 10, 3, 7, 2, 11, 2, 3, 4, 6, 8, 12, 5, 2, 13, 3, 9, 2, 4, 7, 14, 2, 3, 5, 6, 10, 15, 2, 4, 8, 16, 3, 11, 2, 17, 5, 7, 2, 3, 4, 6, 9, 12, 18, 2, 19, 3, 13, 2, 4, 5, 8, 10, 20, 2, 3, 6, 7, 14, 21, 2, 4, 11, 22, 3, 5, 9, 15, 2, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Row n contains row A002808(n) of table A027750.
T(n,k) = A027751(A002808(n),k+1), k = 1..A144925(n). - Reinhard Zumkeller, Mar 29 2014
LINKS
EXAMPLE
The table starts in row n=1 (with the composite 4) as
2;
2,3;
2,4;
3;
2,5;
2,3,4,6;
2,7;
3,5;
2,4,8;
2,3,6,9;
2,4,5,10.
PROG
(Haskell)
a163870 n k = a163870_tabf !! (n-1) !! (k-1)
a163870_row n = a163870_tabf !! (n-1)
a163870_tabf = filter (not . null) $ map tail a027751_tabf
-- Reinhard Zumkeller, Mar 29 2014
CROSSREFS
Cf. A027750.
Cf. A144925 (row lengths), A062825 (row sums), A056608 (left edge), A160180 (right edge).
Sequence in context: A341285 A263323 A263297 * A327664 A155043 A337327
KEYWORD
nonn,tabf
AUTHOR
EXTENSIONS
Entries checked by R. J. Mathar, Sep 22 2009
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)