The profiles of the backtrack tree for the n queens problem, triangle read by rows.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =0a(6) =1a(7) =3a(8) =2a(9) =0a(10) =1a(11) =4a(12) =6a(13) =4a(14) =2a(15) =1a(16) =5a(17) =12a(18) =14a(19) =12a(20) =10a(21) =1a(22) =6a(23) =20a(24) =36a(25) =46a(26) =40a(27) =4a(28) =1a(29) =7