1/6 the number of (n+2) X 3 0..2 arrays with each 3 X 3 subblock containing one of one value, four of another, and four of the last.

A184469

1/6 the number of (n+2) X 3 0..2 arrays with each 3 X 3 subblock containing one of one value, four of another, and four of the last.

Terms

    a(0) =315a(1) =1095a(2) =3705a(3) =12339a(4) =45585a(5) =161739a(6) =559305a(7) =2147931a(8) =7836561a(9) =27667251a(10) =108488889a(11) =401513355a(12) =1432182465a(13) =5674143555a(14) =21145265865a(15) =75792359259a(16) =301775575185

External references