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A082166
a(n) = A006689(n)/n^2.
1
1, 3, 24, 328, 6427, 164765, 5228210, 197897582, 8704544263, 436312502297, 24550259053858, 1532241939881294, 105048412352334420, 7847739530288388636, 634523723233529394594, 55206024491463561241758
OFFSET
1,2
REFERENCES
Valery A. Liskovets, The number of initially connected automata, Kibernetika, (Kiev), No3 (1969), 16-19; Engl. transl.: Cybernetics, v.4 (1969), 259-262.
LINKS
Valery A. Liskovets, Exact enumeration of acyclic automata, Proc. 15th Conf. "Formal Power Series and Algebr. Combin. (FPSAC'03)", 2003.
Valery A. Liskovets, Exact enumeration of acyclic deterministic automata, Discrete Appl. Math., 154, No.3 (2006), 537-551.
MATHEMATICA
b[n_] := b[n] = If[n == 1, 1, n^(2*n)/(n-1)! - Sum[n^(2*(n-i))*b[i]/(n-i)!, {i, 1, n-1}]];
a[n_] := b[n]/n^2;
Array[a, 16] (* Jean-François Alcover, Aug 28 2019 *)
CROSSREFS
Cf. A006689.
Sequence in context: A232693 A319939 A375869 * A354259 A370055 A371007
KEYWORD
easy,nonn
AUTHOR
Valery A. Liskovets, Apr 09 2003
STATUS
approved