A symmetrical triangle T(n, m) = 2*Eulerian(n+1, m) -1, read by rows.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =7a(5) =1a(6) =1a(7) =21a(8) =21a(9) =1a(10) =1a(11) =51a(12) =131a(13) =51a(14) =1a(15) =1a(16) =113a(17) =603a(18) =603a(19) =113a(20) =1a(21) =1a(22) =239a(23) =2381a(24) =4831a(25) =2381a(26) =239a(27) =1a(28) =1a(29) =493