Partitioned 2nd-order Eulerian numbers forming an "Eulerian pyramid" (tetrahedron).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =4a(6) =4a(7) =1a(8) =4a(9) =1a(10) =1a(11) =11a(12) =11a(13) =11a(14) =36a(15) =11a(16) =1a(17) =11a(18) =11a(19) =1a(20) =1a(21) =26a(22) =26a(23) =66a(24) =196a(25) =66a(26) =26a(27) =196a(28) =196a(29) =26