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!)
 A292153 Triangle T(m,k) read by rows, where T(m,k) is the number of ways in which 1<=k<=m positions can be picked in an m X m square grid such that the picked positions have a point symmetry or a line symmetry. 9
 1, 4, 6, 9, 36, 44, 16, 120, 192, 388, 25, 300, 596, 1658, 2138, 36, 630, 1436, 5121, 7216, 22328, 49, 1176, 3024, 13180, 21756, 80192, 126616, 64, 2016, 5568, 29112, 51616, 230784, 394504, 1409328 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The "or" is inclusive, i.e. configurations that have both types of symmetry simultaneously (counted separately in A292154) are included. LINKS FORMULA a(n) = A090642(n) - A292152(n) = A292154(n) + A292155(n) + A292156(n). EXAMPLE The triangle begins:    1;    4,    6;    9,   36,   44;   16,  120,  192,   388;   25,  300,  596,  1658,  2138;   36,  630, 1436,  5121,  7216, 22328;   49, 1176, 3024, 13180, 21756, 80192, 126616; . The following configuration is one of the T(4,3)=a(9)=192 symmetric configurations of 3 points picked from a 4 X 4 grid. It has both types of symmetry.   0 0 0 0   X 0 0 0   0 X 0 0   0 0 X 0 CROSSREFS Cf. A090642, A098485, A098487, A291716, A291717, A291718, A292152, A292154, A292155, A292156. Sequence in context: A292154 A291717 A303699 * A175459 A257652 A107665 Adjacent sequences:  A292150 A292151 A292152 * A292154 A292155 A292156 KEYWORD nonn,tabl AUTHOR Hugo Pfoertner, Sep 17 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 July 30 22:16 EDT 2021. Contains 346365 sequences. (Running on oeis4.)