a(n) = binomial(n+2, 2) + binomial(n+4, 5).

Terms

a(0) =1a(1) =4a(2) =12a(3) =31a(4) =71a(5) =147a(6) =280a(7) =498a(8) =837a(9) =1342a(10) =2068a(11) =3081a(12) =4459a(13) =6293a(14) =8688a(15) =11764a(16) =15657a(17) =20520a(18) =26524a(19) =33859a(20) =42735a(21) =53383a(22) =66056a(23) =81030a(24) =98605a(25) =119106a(26) =142884a(27) =170317a(28) =201811a(29) =237801