a(n) = A131766(n) / 18.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =2a(7) =3a(8) =4a(9) =10a(10) =21a(11) =32a(12) =43a(13) =54a(14) =165a(15) =276a(16) =387a(17) =498a(18) =1109a(19) =2220a(20) =3331a(21) =4442a(22) =5553a(23) =16664a(24) =27775a(25) =38886a(26) =49997a(27) =111108a(28) =222219a(29) =333330