OFFSET
1,4
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..500
MATHEMATICA
rut[n_]:=rut[n]=If[n===1, {{}}, Join@@Function[c, Union[Sort/@Tuples[rut/@c]]]/@IntegerPartitions[n-1]];
Table[Length[Select[rut[n], UnsameQ@@(Count[#, {}, {0, Infinity}]&/@#)&]], {n, 15}]
PROG
(PARI) \\ here R is A055277 as vector of polynomials
R(n) = {my(A = O(x)); for(j=1, n, A = x*(y - 1 + exp( sum(i=1, j, 1/i * subst( subst( A + x * O(x^(j\i)), x, x^i), y, y^i) ) ))); Vec(A)};
seq(n) = {my(M=Mat(apply(p->Colrev(p, n), R(n-1)))); Vec(prod(i=2, #M, 1 + x*Ser(M[i, ])))} \\ Andrew Howroyd, May 20 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 20 2018
EXTENSIONS
Terms a(19) and beyond from Andrew Howroyd, May 20 2018
STATUS
approved