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!)
 A286444 Number of non-equivalent ways to tile an n X n X n triangular area with two 2 X 2 X 2 triangular tiles and an appropriate number (= n^2-8) of 1 X 1 X 1 tiles. 5
 0, 3, 10, 32, 70, 143, 252, 424, 660, 995, 1430, 2008, 2730, 3647, 4760, 6128, 7752, 9699, 11970, 14640, 17710, 21263, 25300, 29912, 35100, 40963, 47502, 54824, 62930, 71935, 81840, 92768, 104720, 117827, 132090, 147648, 164502, 182799, 202540, 223880, 246820, 271523 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,2 COMMENTS Rotations and reflections of tilings are not counted. If they are to be counted, see A286437. Tiles of the same size are indistinguishable. For an analogous problem concerning square tiles, see A279111. LINKS Heinrich Ludwig, Table of n, a(n) for n = 3..100 Heinrich Ludwig, Illustration of tiling a 4X4X4 area Index entries for linear recurrences with constant coefficients, signature (3,-1,-5,5,1,-3,1). FORMULA a(n) = (n^4 -6*n^3 +11*n^2 -12)/12 + IF(MOD(n, 2) = 1, -n +2)/2. G.f.: x^4*(3 + x + 5*x^2 - x^3) / ((1 - x)^5*(1 + x)^2). - Colin Barker, May 12 2017 EXAMPLE There are 3 non-equivalent ways of tiling a triangular area of side 4 with two tiles of side 2 and an appropriate number (= 8) of tiles of side 1. See example in links section. PROG (PARI) concat(0, Vec(x^4*(3 + x + 5*x^2 - x^3) / ((1 - x)^5*(1 + x)^2) + O(x^30))) \\ Colin Barker, May 12 2017 CROSSREFS Cf. A279111, A286437, A286443, A286445, A286446. Sequence in context: A034016 A001403 A072136 * A080406 A036682 A104270 Adjacent sequences:  A286441 A286442 A286443 * A286445 A286446 A286447 KEYWORD nonn,easy AUTHOR Heinrich Ludwig, May 12 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 February 27 07:04 EST 2020. Contains 332299 sequences. (Running on oeis4.)