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 A174903 Number of divisors d of n such that d
 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 1, 0, 0, 2, 0, 1, 0, 0, 0, 5, 0, 0, 0, 1, 0, 5, 0, 0, 0, 0, 1, 6, 0, 0, 0, 3, 0, 3, 0, 0, 3, 0, 0, 7, 0, 0, 0, 0, 0, 3, 0, 3, 0, 0, 0, 9, 0, 0, 1, 0, 0, 3, 0, 0, 0, 3, 0, 9, 0, 0, 2, 0, 1, 2, 0, 5, 0, 0, 0, 9, 0, 0, 0, 1, 0, 9, 1, 0, 0, 0, 0, 9, 0, 0, 1, 2, 0, 2, 0, 1, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,12 COMMENTS a(A174905(n)) = 0; a(A005279(n)) > 0; a(A174904(n)) = n and a(m) <> n for m < A174904(n); a(m)*a(n) <= a(m)*a(n) for m, n coprime. LINKS R. Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE a(12) = #{(2,3), (3,4), (4,6)} = 3; a(15) = #{(3,5)} = 1; a(18) = #{(2,3), (6,9)} = 2; a(20) = #{(4,5)} = 1; a(24) = #{(2,3), (3,4), (4,6), (6,8), (8,12)} = 5. PROG (Haskell) import Data.List (intersect) a174903 n = length [d | let ds = a027750_row n, d <- ds, not \$ null [e | e <- [d+1 .. 2*d-1] `intersect` ds]] -- Reinhard Zumkeller, Sep 29 2014 CROSSREFS Cf. A000005, A005279, A174904, A174905. Sequence in context: A186038 A091009 A204814 * A167163 A005890 A104515 Adjacent sequences: A174900 A174901 A174902 * A174904 A174905 A174906 KEYWORD nonn AUTHOR Reinhard Zumkeller, Apr 01 2010 STATUS approved

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Last modified December 2 07:06 EST 2022. Contains 358493 sequences. (Running on oeis4.)