Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

1,3

At one time it was thought that this might be related to the Hopf algebra structure of perturbative Quantum Field Theory; this later proved not to be the case.

Table of n, a(n) for n=1..20.

Dirk Kreimer, "On the Hopf algebra structure of perturbative quantum field theory"

Dirk Kreimer, Home page

Sequence in context: A128496 A134955 A171887 * A002861 A032200 A130969

Adjacent sequences: A027878 A027879 A027880 * A027882 A027883 A027884

nonn

Dirk Kreimer (kreimer(AT)dipmza.physik.Uni-Mainz.DE)

approved