a(n) = Sum_{k=0..6} binomial(12,k)*binomial(n,k).

Terms

a(0) =1a(1) =13a(2) =91a(3) =455a(4) =1820a(5) =6188a(6) =18564a(7) =49596a(8) =119139a(9) =260743a(10) =527065a(11) =996205a(12) =1778966a(13) =3027038a(14) =4942106a(15) =7785882a(16) =11891061a(17) =17673201a(18) =25643527a(19) =36422659a(20) =50755264a(21) =69525632a(22) =93774176a(23) =124714856a(24) =163753527a(25) =212507211a(26) =272824293a(27) =346805641a(28) =436826650