cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A276163 a(n) is the maximum first-player score difference of a "Coins in a Row" game over all permutations of coins 1..n with both players using a minimax strategy.

Original entry on oeis.org

1, 1, 2, 4, 5, 9, 6, 16, 9, 25, 10, 36, 13, 49, 14, 64
Offset: 1

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Author

Peter Kagey, Aug 22 2016

Keywords

Comments

a(2*n) = n^2 via [1, n+1, 2, n+2, ..., n, 2*n]

Examples

			a(1)  = 1  via [1]
a(2)  = 1  via [1,2]
a(3)  = 2  via [1,2,3]
a(4)  = 4  via [1,3,2,4]
a(5)  = 5  via [1,2,4,3,5]
a(6)  = 9  via [1,4,2,5,3,6]
a(7)  = 6  via [1,2,3,4,6,5,7]
a(8)  = 16 via [1,5,2,6,3,7,4,8]
a(9)  = 9  via [1,2,3,4,6,5,8,7,9]
a(10) = 25 via [1,6,2,7,3,8,4,9,5,10]
For n=4, the first player would take 4, the second player would take 2, the first player would take 3, and the second player would take 1. The resulting score difference would be 4 - 2 + 3 - 1 = 4.
		

References

  • Peter Winkler, Mathematical Puzzles: A Connoisseur's Collection, A K Peters/CRC Press, 2003, pages 1-2.

Crossrefs

Cf. A276164.

Programs

  • Haskell
    minimax [] = 0
    minimax as = max (head as - minimax (tail as)) (last as - minimax (init as))
    a276163 n = maximum $ map minimax $ permutations [1..n]

Extensions

a(11)-a(16) from Bert Dobbelaere, May 03 2025