a(n) = 10*binomial(n,5) + 4*binomial(n,3) + n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =7a(4) =20a(5) =55a(6) =146a(7) =357a(8) =792a(9) =1605a(10) =3010a(11) =5291a(12) =8812a(13) =14027a(14) =21490a(15) =31865a(16) =45936a(17) =64617a(18) =88962a(19) =120175a(20) =159620a(21) =208831a(22) =269522a(23) =343597a(24) =433160a(25) =540525a(26) =668226a(27) =819027a(28) =995932a(29) =1202195