OFFSET
1,2
COMMENTS
Initial terms computed using software at http://users.cecs.anu.edu.au/~bdm/nauty/
Equation (5.8) of Read's paper tells us a(n) = N {S_n[S_4] * S_{2n}[S_2]}, where we are working with cycle index polynomials. - Jason Kimberley, Oct 05 2009
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..40
R. de Mello Koch and S. Ramgoolam, Strings from Feynman graph counting: Without large N, Phys. Rev. D 85 (2012) 026007
R. C. Read, The enumeration of locally restricted graphs (I), J. London Math. Soc. 34 (1959) 417-436.
FORMULA
Euler transform of A085549. - Andrew Howroyd, Mar 15 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Brendan McKay, Apr 15 2007
EXTENSIONS
Using equation (5.8) of Read's paper, new terms a(17)-a(19) were computed in MAGMA by Jason Kimberley, Oct 05 2009
Four more terms a(20)-a(23) also computed by Jason Kimberley, Nov 09 2009
STATUS
approved