Number of (n+2)X(3+2) 0..3 arrays with every 3X3 subblock row and column sum nonprime and every diagonal and antidiagonal sum prime.
A251840
Number of (n+2)X(3+2) 0..3 arrays with every 3X3 subblock row and column sum nonprime and every diagonal and antidiagonal sum prime.
Terms
- a(0) =641a(1) =828a(2) =1803a(3) =2890a(4) =8582a(5) =21748a(6) =40492a(7) =128431a(8) =339592a(9) =639794a(10) =2087597a(11) =5632271a(12) =10609658a(13) =35199882a(14) =96069006a(15) =180868454a(16) =605781397a(17) =1663988392a(18) =3131743910a(19) =10543905961a(20) =29063878897a(21) =54690404276a(22) =184648426284a(23) =509929622436
External references
- oeis: A251840