OFFSET
1,3
REFERENCES
F. Harary and E. Palmer, Graphical Enumeration, (1973), p. 30, Problem 1.14.
E. M. Palmer and R. C. Read, on the number of plane 2-trees, J. Lond. Math. Soc., 6 (1973), 583-592.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..300
Allan Bickle, A Survey of Maximal k-degenerate Graphs and k-Trees, Theory and Applications of Graphs 0 1 (2024) Article 5.
E. M. Palmer and R. C. Read, On the number of plane 2-trees, J. Lond. Math. Soc., 6 (1973), 583-592. [Annotated and corrected scanned copy]
FORMULA
a(n) = n*(n-1)^2*(5*n-10)!/(4*n-6)!.
MAPLE
[0, seq(n*(n-1)^2*(5*n-10)!/(4*n-6)!, n=2..20) ];
MATHEMATICA
Join[{0}, Table[n*(n-1)^2*(5*n-10)!/(4*n-6)!, {n, 2, 30}]] (* G. C. Greubel, Nov 02 2022 *)
PROG
(Magma) [0] cat [n*(n-1)^2*Factorial(5*n-10)/Factorial(4*n-6): n in [2..30]]; // G. C. Greubel, Nov 02 2022
(SageMath) [0]+[n*(n-1)^2*factorial(5*n-10)/factorial(4*n-6) for n in range(2, 30)] # G. C. Greubel, Nov 02 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved