Sixth diagonal of triangle A064094.

Terms

a(0) =1a(1) =42a(2) =381a(3) =1606a(4) =4641a(5) =10746a(6) =21517a(7) =38886a(8) =65121a(9) =102826a(10) =154941a(11) =224742a(12) =315841a(13) =432186a(14) =578061a(15) =758086a(16) =977217a(17) =1240746a(18) =1554301a(19) =1923846a(20) =2355681a(21) =2856442a(22) =3433101a(23) =4092966a(24) =4843681a(25) =5693226