OFFSET
3,2
COMMENTS
Table 2 of Palmer and Read paper gives incorrect value a(10) = 457025. - Sean A. Irvine, Feb 12 2016
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
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.
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
G.f.: P(x) + (1/2) * x^2 * ((1 - T(x^2))^(-1) - 1) + (2/3) * x^3 * (1 - T(x^3))^(-2) where P(x) = Sum_{k>=1} ((k * (k - 1) * (5*k-10)! / (4*k-6)!) * x^k / k!) is the e.g.f. of A003092 and T(x) = Sum_{k>=1} (((5 * k - 2)!/ (4 * k - 1)!) * x^k / k!) is the e.g.f. of A120348. - Sean A. Irvine, Feb 12 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(10) corrected and more terms from Sean A. Irvine, Feb 12 2016
STATUS
approved