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 A320065 a(n) is the smallest integer i such that binomial(2i,i) > n. 0
 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The formula can be proved by using Stirling's formula to estimate the central binomial coefficient binomial(2i,i). LINKS FORMULA a(n) = (log n)/(log 4) + (log log n)/(log 16) + O(1). MATHEMATICA Array[Block[{i = 1}, While[Binomial[2 i, i] <= #, i++]; i] &, 105] (* Michael De Vlieger, Oct 22 2018 *) CROSSREFS Cf. A000984. Sequence in context: A069624 A092139 A084558 * A163291 A156875 A066339 Adjacent sequences:  A320062 A320063 A320064 * A320066 A320067 A320068 KEYWORD nonn AUTHOR David Lewis, Oct 22 2018 STATUS approved

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Last modified September 18 18:15 EDT 2019. Contains 327178 sequences. (Running on oeis4.)