Half the number of 0..n arrays of length 5 with second differences nonzero.

Terms

a(0) =8a(1) =66a(2) =350a(3) =1134a(4) =3010a(5) =6724a(6) =13544a(7) =24870a(8) =42952a(9) =70060a(10) =109638a(11) =165098a(12) =241342a(13) =343074a(14) =476992a(15) =649304a(16) =868684a(17) =1143156a(18) =1483630a(19) =1900056a(20) =2405958a(21) =3013428a(22) =3738744a(23) =4596484a(24) =5605944a(25) =6784266a(26) =8154174a(27) =9735586a(28) =11554762a(29) =13634780