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Some Postage Stamp 2-Bases
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John P. Robinson

Coordinated Laboratory for Computational Genomics

University of Iowa

Iowa City, IA 52242

USA

**Abstract:**

A set of *k* integers is a 2-basis if every positive
integer up to *n* can be expressed as the sum of no more than 2 values
from the set; an extremal 2-basis is one for which *n* is as large as
possible. A new algorithm extends the lower bound of Mossige for
symmetric bases. An assumed modulo structure is combined with local
search. These 2-bases match all known extremal values for *k* from 11
to 20. Bases out to *k* = 82 are given.

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(Concerned with sequence
A001212.)

Received September 9 2008;
revised version received November 19 2008.
Published in *Journal of Integer Sequences*, December 14 2008.

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