659002251789domain: NAppears in sequencesa(n) = 7*3^n.at n=23A0050329th binomial transform of (1,1,0,0,0,0,0,...).at n=12A081109a(n) = (7*3^n - 4*0^n)/3.at n=24A082541Expansion of (1-3*x+12*x^2)/((1-3*x)*(1+3*x)).at n=24A091103a(n) = 3*a(n-1) for n>2; a(0)=1, a(1)=3, a(2)=7.at n=25A141495