Triangle of coefficients arising in calculation of A002872 and A002874 (sorting numbers).

Terms

a(0) =1a(1) =2a(2) =1a(3) =5a(4) =1a(5) =6a(6) =15a(7) =1a(8) =11a(9) =30a(10) =52a(11) =1a(12) =20a(13) =80a(14) =150a(15) =203a(16) =1a(17) =37a(18) =210a(19) =525a(20) =780a(21) =877a(22) =1a(23) =70a(24) =560a(25) =1785a(26) =3395a(27) =4263a(28) =4140a(29) =1