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%I
%S 1,1,1,1,2,1,1,1,2,1,1,1,1,2,1,1,1,1,2,2,1,1,1,1,1,1,2,1,1,1,1,1,1,2,
%T 2,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,2,2,1,1,1,1,1,1,1,1,1,2,1,1,1,
%U 2,1,1,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1
%N Number of rows in which n appears in Pascal's triangle (A007318).
%C a(A180058(n)) = n and a(m) < n for m < A180058(n); a(A182237(n)) = 2; a(A098565(n)) = 3. - _Reinhard Zumkeller_, Dec 24 2012
%D L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 93, #47.
%D C. S. Ogilvy, Tomorrow's Math. 2nd ed., Oxford Univ. Press, 1972, p. 96.
%D D. Singmaster, How often does an integer occur as a binomial coefficient?, Amer. Math. Monthly, 78 (1971), 385-386.
%H T. D. Noe, <a href="/A059233/b059233.txt">Table of n, a(n) for n=2..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PascalsTriangle.html">Pascal's Triangle</a>
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Singmaster's_conjecture">Singmaster's conjecture</a>
%H <a href="/index/Pas#Pascal">Index entries for triangles and arrays related to Pascal's triangle</a>
%e 6 appears in both row 4 and row 6 in Pascal's triangle, therefore a(6)=2.
%o (Haskell)
%o a059233 n = length $ filter (n `elem`) $
%o take (fromInteger n) $ tail a007318_tabl
%o a059233_list = map a059233 [2..]
%o -- _Reinhard Zumkeller_, Dec 24 2012
%Y Cf. A003016, A003015.
%K easy,nice,nonn
%O 2,5
%A _Fabian Rothelius_, Jan 20 2001
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