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!)
 A220195 Sum of neighbor maps: log base 2 of the number of n X n binary arrays indicating the locations of corresponding elements equal to the sum mod 2 of their horizontal and vertical neighbors in a random 0..1 n X n array 0
 1, 4, 9, 12, 23, 36, 49, 64, 73, 100, 115, 144, 169, 192, 225, 248, 287, 324, 345, 400, 441, 484, 515, 572, 625, 676, 729, 784, 831, 880, 961, 1004, 1073, 1152, 1219, 1296, 1369, 1444, 1489, 1600, 1679, 1764, 1849, 1932, 2025, 2116, 2179, 2304, 2393, 2492 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A220196. Also, equals n^2 - A159257(n). The entries describe the rank of the Lights Out problem of size n (see A159257). LINKS EXAMPLE Some solutions for n=3 ..1..1..0....0..1..1....0..0..0....1..1..1....0..1..0....1..0..0....0..0..1 ..1..0..1....0..0..0....0..0..1....1..1..0....0..0..0....0..0..1....1..0..1 ..1..0..0....1..0..0....1..0..0....0..1..0....1..1..1....0..0..0....1..1..0 MATHEMATICA Table[n^2 - (First[Dimensions[NullSpace[AdjacencyMatrix[GridGraph[{n, n}]] + IdentityMatrix[n*n], Modulus->2]]]), {n, 1, 40}] (* Vincenzo Librandi, Feb 10 2017 *) CROSSREFS Cf. A159257, A220196. Sequence in context: A186130 A051233 A124623 * A221355 A197681 A197624 Adjacent sequences:  A220192 A220193 A220194 * A220196 A220197 A220198 KEYWORD nonn AUTHOR R. H. Hardin, Dec 07 2012 EXTENSIONS More terms from Vincenzo Librandi, Feb 10 2017 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 November 27 12:51 EST 2021. Contains 349394 sequences. (Running on oeis4.)