OFFSET
1,4
REFERENCES
F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 18, Table 1.5.1.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..80
MATHEMATICA
m = 16;
CoefficientList[Sum[x^j*j!*2^Binomial[j, 2], {j, 1, m}] + O[x]^n, x]* CoefficientList[(Sum[x^j/(j!*2^Binomial[j, 2]), {j, 1, n}] + O[x]^m)^4/24 + O[x]^m, x] // Rest (* Jean-François Alcover, Sep 06 2019, from PARI *)
PROG
(PARI) seq(n)={Vec(serconvol(sum(j=1, n, x^j*j!*2^binomial(j, 2)) + O(x*x^n), (sum(j=1, n, x^j/(j!*2^binomial(j, 2))) + O(x*x^n))^4)/24, -n)} \\ Andrew Howroyd, Nov 30 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 07 2001
STATUS
approved