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.

Showing 1-2 of 2 results.

A090245 Maximum numbers of cards that would have no SET in an n-attribute version of the SET card game.

Original entry on oeis.org

1, 2, 4, 9, 20, 45, 112
Offset: 0

Views

Author

Hans Havermann, Jan 23 2004

Keywords

Comments

Or, largest size of an n-dimensional capset (i.e., a subset of (Z/3Z)^n that does not contain any lines {a, a+r, a+2r}). - Terence Tao, Feb 20 2009
Or, size of maximal cap in the affine geometry AG(n+1,3). - N. J. A. Sloane, Oct 25 2014

Crossrefs

Formula

a(n) <= A003142(n).
Asymptotically, a(n) = O(3^n/n) and a(n) > (2.21...)^n. - Terence Tao, Feb 20 2009
Asymptotically, a(n) = o(2.756^n). - David Radcliffe, May 30 2016

Extensions

a(6) from Terence Tao, Feb 20 2009
Edited by N. J. A. Sloane, Feb 21 2009
Edited by Andrey Zabolotskiy, Mar 01 2024

A156989 Largest size of a subset of {1,2,3}^n that does not contain any combinatorial lines (i.e., strings formed by 1, 2, 3, and at least one instance of a wildcard x, with x then substituted for 1, 2, or 3, e.g. 12x3x gives the combinatorial line 12131, 12232, 12333.)

Original entry on oeis.org

1, 2, 6, 18, 52, 150, 450
Offset: 0

Views

Author

Terence Tao, Feb 20 2009

Keywords

Comments

The density Hales-Jewett theorem implies that a(n) = o(3^n). a(n) is studied further in the polymath1 project, see link below.

Examples

			For n=2, one example that shows a(2) is at least 6 is { 11, 13, 22, 23, 31, 32 }.
		

Crossrefs

Bounded below by A003142. Cf. A000244, A090245.
Showing 1-2 of 2 results.