3221159936domain: NAppears in sequencesRelates row sums of Pascal's triangle to expansion of cos(x)/exp(x).at n=31A100216a(n) = 2*a(n-1) + 2*a(n-2) - 4*a(n-3) with n>2, a(0)=0, a(1)=1, a(2)=3.at n=31A135094a(n) = (3*2^n - 2) * 2^n.at n=15A165665