263331

Appears in sequences

• a(n) = -3*a(n-1) + 9*a(n-2) + 3*a(n-3), with a(0)=3, a(1)=-3, a(2)=27.at n=8A215829
• Number of (n+1) X 3 0..1 matrices with each 2 X 2 subblock idempotent.at n=20A224544