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.

User: Peter M. Huggins

Peter M. Huggins's wiki page.

Peter M. Huggins has authored 1 sequences.

A246536 a(n) = number of strings (including the empty string) over an alphabet of size n that do not have any substrings of length > 1 that appear more than once in the string.

Original entry on oeis.org

3, 25, 1885, 3636297, 327094648711
Offset: 1

Views

Author

Peter M. Huggins, Aug 28 2014

Keywords

Comments

Here "substrings" have no "gaps", i.e. a substring means a subsequence of characters from the original string using contiguous indices.
The number of De Bruijn sequences B(n,2) (which has a known explicit formula) can be used to give the fairly tight lower bound that a(n) > 2*n^2*B(n,2). See A166315.

Crossrefs

Cf. A166315.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.