This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A007816 Number of abstract simplicial 2-complexes on {1,2,3,...,n+3} which triangulate the 2-sphere: C(n+3,2)*(4n+1)!/(3n+3)!. 3
 1, 10, 195, 5712, 223440, 10929600, 641277000, 43859692800, 3424685806080, 300495408595200, 29262949937020800, 3131187613956864000, 365112996737448960000, 46075561988281233408000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES Foulds, L. R. Enumeration of graph theoretic solutions for facilities layout. Proceedings of the sixteenth Southeastern international conference on combinatorics, graph theory and computing (Boca Raton, Fla., 1985). Congr. Numer. 48 (1985), 87--99. MR0830702(87f:90045). See Table 2. - From N. J. A. Sloane, Apr 06 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..200 William T. Tutte, A census of planar triangulations, Canad. J. Math. 14 (1962), 21-38. MAPLE A007816:=n->binomial(n+3, 2)*(4*n+1)!/(3*n+3)!; seq(A007816(n), n=1..20); MATHEMATICA Table[Binomial[n+3, 2] (4n+1)!/(3n+3)!, {n, 20}] (* Harvey P. Dale, May 16 2012 *) PROG (MAGMA) [Binomial(n+3, 2)*Factorial(4*n+1)/Factorial(3*n+3): n in [1..20]]; // Vincenzo Librandi, May 21 2012 CROSSREFS Sequence in context: A006436 A252974 A187652 * A126463 A239766 A294047 Adjacent sequences:  A007813 A007814 A007815 * A007817 A007818 A007819 KEYWORD nonn,easy,nice AUTHOR Victor Reiner (reiner(AT)math.umn.edu), Paul Edelman (edelman(AT)math.umn.edu) 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 23 13:11 EDT 2018. Contains 316528 sequences. (Running on oeis4.)