a(n) is the smallest number of grains of sand placed at the center square of a (2n-1) X (2n-1) table so that some grains drop off the table by the end of the diffusion process.

A259013

a(n) is the smallest number of grains of sand placed at the center square of a (2n-1) X (2n-1) table so that some grains drop off the table by the end of the diffusion process.