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A006638
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Restricted postage stamp problem with n denominations and 2 stamps.
(Formerly M1088)
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2
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2, 4, 8, 12, 16, 20, 26, 32, 40, 44, 54, 64, 72, 80, 92, 104, 116, 128, 140, 152, 164, 180, 196, 212, 228, 244, 262, 280, 298, 316, 338, 360, 382, 404, 426, 448, 470, 492, 514, 536, 562, 588, 614, 644, 674, 704, 734
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OFFSET
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1,1
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COMMENTS
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a(n) = largest span (range) attained by a restricted additive 2-basis of length n; an additive 2-basis is restricted if its span is exactly twice its largest element. - Jukka Kohonen, Apr 23 2014
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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S. S. Wagstaff, Jr., Additive h-bases for n, pp. 302-327 of Number Theory Carbondale 1979, Lect. Notes Math. 751 (1982).
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EXAMPLE
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a(10)=44: For example, the basis {0, 1, 2, 3, 7, 11, 15, 17, 20, 21, 22} has 10 nonzero elements, and all integers between 0 and 44 can be expressed as sums of two elements of the basis. Currently n=10 is the only known case where A006638 differs from A001212. - Jukka Kohonen, Apr 23 2014
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Extended up to a(41) from Kohonen (2014), by Jukka Kohonen, Apr 23 2014
Extended up to a(47) from Kohonen (2015), by Jukka Kohonen, Mar 14 2015
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STATUS
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approved
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