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 A003016 Number of occurrences of n as an entry in rows <= n of Pascal's triangle (A007318). (Formerly M0227) 15
 0, 3, 1, 2, 2, 2, 3, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 2, 2, 2, 3, 4, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Or, number of occurrences of n as a binomial coefficient. Sequence A138496 gives record values and where they occur. - Reinhard Zumkeller, Mar 20 2008 REFERENCES L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 93, #47. C. S. Ogilvy, Tomorrow's Math. 2nd ed., Oxford Univ. Press, 1972, p. 96. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. Zumkeller, Table of n, a(n) for n = 0..10000 H. L. Abbott, P. Erdős and D. Hanson, On the numbers of times an integer occurs as a binomial coefficient, Amer. Math. Monthly, (1974), 256-261. Daniel Kane, New Bounds on the Number of Representations of t as a Binomial Coefficient, INTEGERS, Electronic J. of Combinatorial Number Theory, Vol. 4, Paper A7, 2004. D. Singmaster, How often does an integer occur as a binomial coefficient?, Amer. Math. Monthly, 78 (1971), 385-386. Eric Weisstein's World of Mathematics, Pascal's Triangle MATHEMATICA a[0] = 0; t = {{1}}; a[n_] := Count[ AppendTo[t, Table[ Binomial[n, k], {k, 0, n}]], n, {2}]; Table[a[n], {n, 0, 101}] (* Jean-François Alcover, Feb 20 2012 *) PROG (Haskell) a003016 n = sum \$ map (fromEnum . (== n)) \$                       concat \$ take (fromInteger n + 1) a007318_tabl -- Reinhard Zumkeller, Apr 12 2012 (PARI) f(n, k)=my(g=lngamma(k+1)+log(n)); binomial(round(solve(N=k, n+k, lngamma(N+1) - lngamma(N-k+1) - g)), k)==n a(n)=if(n<3, [0, 3, 1][n+1], 2+2*sum(k=2, (n-1)\2, f(n, k))+if(n%2, , f(n, n/2))) \\ Charles R Greathouse IV, Oct 22 2013 CROSSREFS Cf. A003015, A059233, A138496, A180058. Sequence in context: A185736 A144148 A085247 * A328848 A108121 A161916 Adjacent sequences:  A003013 A003014 A003015 * A003017 A003018 A003019 KEYWORD nonn,nice,easy AUTHOR EXTENSIONS More terms from Erich Friedman Edited by N. J. A. Sloane, Nov 18 2007, at the suggestion of Max Alekseyev STATUS approved

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Last modified February 28 08:28 EST 2020. Contains 332323 sequences. (Running on oeis4.)