a(n) = (5*n+1)*(5*n+4).

Terms

a(0) =4a(1) =54a(2) =154a(3) =304a(4) =504a(5) =754a(6) =1054a(7) =1404a(8) =1804a(9) =2254a(10) =2754a(11) =3304a(12) =3904a(13) =4554a(14) =5254a(15) =6004a(16) =6804a(17) =7654a(18) =8554a(19) =9504a(20) =10504a(21) =11554a(22) =12654a(23) =13804a(24) =15004a(25) =16254a(26) =17554a(27) =18904a(28) =20304a(29) =21754