Triangular array for David G. Cantor's sigma function.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =3a(8) =4a(9) =3a(10) =1a(11) =4a(12) =10a(13) =24a(14) =10a(15) =1a(16) =5a(17) =20a(18) =105a(19) =160a(20) =105a(21) =1a(22) =6a(23) =35a(24) =336a(25) =1260a(26) =3360a(27) =1260a(28) =1a(29) =7