A triangle of structure called "Polynomial on residue classes" (PORC).

Terms

a(0) =1a(1) =2a(2) =2a(3) =5a(4) =5a(5) =5a(6) =14a(7) =14a(8) =15a(9) =15a(10) =51a(11) =51a(12) =67a(13) =76a(14) =77a(15) =267a(16) =267a(17) =504a(18) =633a(19) =684a(20) =731a(21) =2328a(22) =2328a(23) =9310a(24) =9310a(25) =34297a(26) =62440a(27) =113147