OFFSET
0,6
REFERENCES
F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures.
F. Harary and E. M. Palmer, Graphical Enumeration, p. 71
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..500
C. G. Bower, Transforms (2)
F. Harary and R. Z. Norman, The Dissimilarity Characteristic of Husimi Trees, Annals of Mathematics, 58 1953, pp. 134-141.
F. Harary and G. E. Uhlenbeck, On the Number of Husimi Trees, Proc. Nat. Acad. Sci. USA vol. 39 pp. 315-322 1953
N. J. A. Sloane, Transforms
FORMULA
Shifts left under transform T where Ta = EULER(BIK(a)-a).
PROG
(PARI)
BIK(p)={(1/(1-p) + (1+p)/subst(1-p, x, x^2))/2}
EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
seq(n)={my(p=O(x)); for(n=1, n, p=x+x^2*Ser(EulerT(Vec(BIK(p)-1)-Vec(p)))); concat([0], Vec(p))} \\ Andrew Howroyd, Aug 30 2018
CROSSREFS
KEYWORD
nonn,eigen
AUTHOR
Christian G. Bower, Nov 15 1998
STATUS
approved