OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..200
FORMULA
Binomial transform of b(1) = 1, b(n) = A134958(n) otherwise.
EXAMPLE
The a(2) = 7 hypertrees are the following:
{}
{{1}}
{{2}}
{{1,2}}
{{1},{1,2}}
{{2},{1,2}}
{{1},{2},{1,2}}
PROG
(PARI) \\ here b(n) is A134958 with b(1)=1.
b(n)=if(n<2, n>=0, 2^n*sum(i=0, n, stirling(n-1, i, 2)*n^(i-1)));
a(n)=sum(k=0, n, binomial(n, k)*b(k)); \\ Andrew Howroyd, Aug 27 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 22 2018
STATUS
approved