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 A066063 Size of the smallest subset S of T={0,1,2,...,n} such that each element of T is the sum of two elements of S. 2
 1, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS If one counts all subsets S of T={0,1,2,...n} such that each number in T is the sum of two elements of S, sequence A066062 is obtained. Since each k-subset of S covers at most binom(k + 1, 2) members of T, we have binom(A066063(n) + 1, 2) >= n + 1. It follows that A002024(n-1) is a lower bound. - Rob Pratt, May 14 2004 This is an instance of the <= 2-stamp postage problem with n denominations. For n > 0, A066063(n) = 1 + the smallest i such that A001212(i) >= n (adding one adjusts for the fact that A001212 has offset 1). - Tim Peters (tim.one(AT)comcast.net), Aug 25 2006 LINKS EXAMPLE For n=2, it is clear that S={0,1} is the unique subset of {0,1,2} that satisfies the definition, so a(2)=2. CROSSREFS Cf. A066062. Cf. A002024. Cf. A001212. Sequence in context: A277903 A102515 A276571 * A123087 A071868 A179390 Adjacent sequences:  A066060 A066061 A066062 * A066064 A066065 A066066 KEYWORD nonn AUTHOR John W. Layman, Dec 01 2001 STATUS approved

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Last modified September 20 13:59 EDT 2019. Contains 327238 sequences. (Running on oeis4.)