The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A191506 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 horizontally or vertically neighboring 1 1
 2, 5, 25, 195, 2475, 53324, 1872113, 109037035, 10508450377, 1672058437225, 440124911303718, 191498508664286039, 137739615464486164780, 163796811382099494131871, 322006666961136384120723488 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Ron Hardin, Table of n, a(n) for n = 1..26 EXAMPLE Some solutions for n=4 ..1..0..1..0....0..0..0..1....0..1..0..0....0..0..0..1....1..0..0..1 ..0..1..0..1....0..0..0..1....1..0..0..0....0..0..1..0....0..1..0..0 ..1..0..1..0....0..0..1..0....0..0..1..0....0..1..0..0....0..0..0..1 ..0..1..0..1....1..1..0..1....0..0..0..1....1..0..0..1....1..0..1..0 CROSSREFS Sequence in context: A268120 A324263 A049650 * A139007 A015486 A191951 Adjacent sequences:  A191503 A191504 A191505 * A191507 A191508 A191509 KEYWORD nonn AUTHOR R. H. Hardin Jun 04 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 28 07:07 EST 2020. Contains 331317 sequences. (Running on oeis4.)