The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A262326 Number of (n+1) X (2+1) 0..1 arrays with each row and column divisible by 3, read as a binary number with top and left being the most significant bits. 2
 3, 5, 15, 33, 99, 261, 783, 2241, 6723, 19845, 59535, 177633, 532899, 1595781, 4787343, 14353281, 43059843, 129153285, 387459855, 1162300833, 3486902499, 10460471301, 31381413903, 94143533121, 282430599363, 847289672325 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 2 of A262332. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 3*a(n-1) + 3*a(n-2) - 9*a(n-3). Conjectures from Colin Barker, Mar 20 2018: (Start) G.f.: x*(3 - 4*x - 9*x^2) / ((1 - 3*x)*(1 - 3*x^2)). a(n) = 2*3^(n/2-1) + 3^(n-1) for n even. a(n) = 2*3^((n-3)/2+1) + 3^(n-1) for n odd. (End) EXAMPLE Some solutions for n=4: ..0..1..1....0..0..0....0..1..1....0..0..0....1..1..0....0..0..0....1..1..0 ..1..1..0....1..1..0....0..1..1....0..0..0....1..1..0....1..1..0....0..0..0 ..0..0..0....1..1..0....1..1..0....0..0..0....0..1..1....1..1..0....1..1..0 ..0..1..1....0..1..1....1..1..0....1..1..0....0..1..1....1..1..0....0..0..0 ..1..1..0....0..1..1....0..0..0....1..1..0....0..0..0....1..1..0....1..1..0 CROSSREFS Cf. A262332. Sequence in context: A182143 A193649 A186341 * A148499 A148500 A148501 Adjacent sequences: A262323 A262324 A262325 * A262327 A262328 A262329 KEYWORD nonn AUTHOR R. H. Hardin, Sep 18 2015 STATUS approved

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

Last modified March 2 01:29 EST 2024. Contains 370447 sequences. (Running on oeis4.)