A261187 a(n) = (2^(n-1))!*y(n) where y(n)=1/2*(y(n-1))^2+1 for n>=2 and y(1)=1.

1, 3, 51, 131355, 131953155208875, 5496027066067360087228913484456796875, 27805296606704951937976342299927372748633425216234990144120838935506416477839670037841796875

Offset

1,2

Comments

a(n) is also the number of knockout tournament seedings that satisfy the symmetry property.

Links

Table of n, a(n) for n=1..7.

Alexander Karpov, A theory of knockout tournament seedings, Heidelberg University, AWI Discussion Paper Series, No. 600.

Mathematica

Table[(2^(n-1))!*FoldList[(1/2)*(#1)^2+1&, 1, Range[2, 7]][[n]], {n, 1, 7}] (* Ivan N. Ianakiev, Aug 25 2015 *)

Crossrefs

Cf. A067667 (number of seedings).

Sequence in context: A307022 A330302 A227067 * A347509 A273923 A037106

Adjacent sequences: A261184 A261185 A261186 * A261188 A261189 A261190

Keyword

nonn

Author

Alexander Karpov, Aug 11 2015

Status

approved