a(n) = (11*n + 4)*C(n+3, 3)/4.

Terms

a(0) =1a(1) =15a(2) =65a(3) =185a(4) =420a(5) =826a(6) =1470a(7) =2430a(8) =3795a(9) =5665a(10) =8151a(11) =11375a(12) =15470a(13) =20580a(14) =26860a(15) =34476a(16) =43605a(17) =54435a(18) =67165a(19) =82005a(20) =99176a(21) =118910a(22) =141450a(23) =167050a(24) =195975a(25) =228501a(26) =264915a(27) =305515a(28) =350610a(29) =400520