Triangle read by rows: coefficients of Yablonskii-Vorob'ev polynomials.

Terms

a(0) =1a(1) =1a(2) =1a(3) =-1a(4) =1a(5) =-5a(6) =-5a(7) =1a(8) =-15a(9) =0a(10) =-175a(11) =1a(12) =-35a(13) =175a(14) =-1225a(15) =-12250a(16) =6125a(17) =1a(18) =-70a(19) =1155a(20) =-9800a(21) =-67375a(22) =-1414875a(23) =4716250a(24) =2358125a(25) =1a(26) =-126a(27) =4725a(28) =-80850a(29) =242550