Number of third differences of arrays of length 6 of numbers in 0..n.

Terms

a(0) =63a(1) =621a(2) =2511a(3) =6419a(4) =12947a(5) =22727a(6) =36471a(7) =54851a(8) =78539a(9) =108207a(10) =144527a(11) =188171a(12) =239811a(13) =300119a(14) =369767a(15) =449427a(16) =539771a(17) =641471a(18) =755199a(19) =881627a(20) =1021427a(21) =1175271a(22) =1343831a(23) =1527779a(24) =1727787a(25) =1944527a(26) =2178671a(27) =2430891a(28) =2701859a(29) =2992247