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The Integer Sequence A002620 and Upper Antagonistic Functions
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Sam E. Speed

Department of Mathematical Sciences

University of Memphis

Memphis, TN 38152-3240

USA

**Abstract:**
This paper shows the equivalence of various integer functions to
the integer sequence A002620, and to the maximum of the product
of certain pairs of combinatorial or graphical invariants. This maximum is the same as
the upper bound of the Nordhaus-Gaddum inequality and related to Turán's number.
The computer algebra program `MAPLE` is used for solutions of linear
recurrence and differential equations in some of the proofs.
Chapter three of *The Encyclopedia of Integer Sequences* by Sloane and Plouffe
describes the usefulness of apparently different expressions of an integer sequence.

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(Concerned with sequence
A002620
.)

Received January 10 2001;
revised versions received March 19 2002; February 26, 2003.
Published in *Journal of Integer Sequences* March 2, 2003.

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