This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A280789 Triangle read by rows: number of topologically distinct sets of N circles with one pair touching, classified according to number of factors. 0
 1, 2, 1, 6, 3, 1, 16, 10, 3, 1, 46, 30, 11, 3, 1, 128, 91, 34, 11, 3, 1, 364, 268, 108, 35, 11, 3, 1, 1029, 790, 327, 112, 35, 11, 3, 1, 2930, 2308, 992, 344, 113, 35, 11, 3, 1, 8344, 6737, 2962, 1055, 348, 113, 35, 11, 3, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS R. J. Mathar, Topologically Distinct Sets of Non-intersecting Circles in the Plane, arXiv:1603.00077, 2016. EXAMPLE Triangle begins: 1, 2,1, 6,3,1, 16,10,3,1, 46,30,11,3,1, 128,91,34,11,3,1, 364,268,108,35,11,3,1, 1029,790,327,112,35,11,3,1, ... CROSSREFS Row sums give A269800. Sequence in context: A059300 A321331 A046803 * A121468 A168151 A213221 Adjacent sequences:  A280786 A280787 A280788 * A280790 A280791 A280792 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Jan 20 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 19 16:02 EST 2019. Contains 320311 sequences. (Running on oeis4.)