110769550

Appears in sequences

• Number of non-vanishing Feynman diagrams of order 2n for the electron or the photon propagators in quantum electrodynamics.at n=9A005411
• A(n,k) is the sum over all Dyck paths of semilength n of products over all peaks p of (x_p+k*y_p)/y_p, where x_p and y_p are the coordinates of peak p; square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=54A258219