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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A239893 Irregular triangle read by rows: T(n,k) is the number of sensed 3-connected planar maps with n >= 4 faces and k >= 4 vertices. 6
 1, 0, 1, 1, 0, 1, 3, 2, 2, 0, 0, 2, 11, 16, 10, 6, 0, 0, 2, 16, 69, 127, 128, 60, 17, 0, 0, 0, 10, 127, 541, 1188, 1441, 1032, 386, 73, 0, 0, 0, 6, 128, 1188, 5096, 11982, 17265, 15466, 8582, 2652, 389, 0, 0, 0, 0, 60, 1441, 11982, 50586, 127765, 206880, 222472, 158057, 71980, 18914, 2274 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,7 COMMENTS T(n,k) is the number of polyhedra with n faces and k vertices up to orientation preserving isomorphisms. The number of edges is n+k-2. - Andrew Howroyd, Mar 27 2021 LINKS Andrew Howroyd, Table of n, a(n) for n = 4..199 (rows 4..17) Gunnar Brinkmann and Brendan McKay, Fast generation of planar graphs (expanded edition), Table 9-11. Timothy R. Walsh, Efficient enumeration of sensed planar maps, Discrete Math. 293 (2005), no. 1-3, 263--289. MR2136069 (2006b:05062). Timothy R. S. Walsh, Counting nonisomorphic three-connected planar maps, J. Combin. Theory Ser. B 32 (1982), no. 1, 33-44. FORMULA T(n,k) = T(k,n). - Andrew Howroyd, Mar 27 2021 EXAMPLE Triangle begins: 1 0 1 1 0 1 3  2   2 0 0 2 11  16   10     6 0 0 2 16  69  127   128    60     17 0 0 0 10 127  541  1188  1441   1032    386     73 0 0 0  6 128 1188  5096 11982  17265  15466   8582   2652   389 0 0 0  0  60 1441 11982 50586 127765 206880 222472 158057 71980 18914 2274 ... CROSSREFS Row and column sums are A119501. Main diagonal is A342057. The unsensed version is A212438. Cf. A005645 (by edges). Sequence in context: A152790 A247602 A201902 * A178609 A144948 A108335 Adjacent sequences:  A239890 A239891 A239892 * A239894 A239895 A239896 KEYWORD nonn,tabf AUTHOR N. J. A. Sloane, Apr 03 2014 EXTENSIONS Terms a(67) and beyond from Andrew Howroyd, Mar 27 2021 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 June 27 08:36 EDT 2022. Contains 354891 sequences. (Running on oeis4.)