Triangle of numbers of irreducible Euler sums.

Terms

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