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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, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12
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 binomial(k + 1, 2) members of T, we have binomial(a(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, a(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
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
KEYWORD
nonn,more
AUTHOR
John W. Layman, Dec 01 2001
EXTENSIONS
a(27)-a(50) from Rob Pratt, Aug 13 2020
STATUS
approved