Empirical: a(n) = (1/7353420799762759680000000)*n^30 + (1/490228053317517312000000)*n^29 + (34757/94275925977648070656000000)*n^28 + (189757/24441906734945796096000000)*n^27 + (235252351/576130658752293765120000000)*n^26 + (87963019/8863548596189134848000000)*n^25 + (639235967/2189817888470256844800000)*n^24 + (84556141633/12408968034664788787200000)*n^23 + (71931478439/476047367058751488000000)*n^22 + (7866285569/2581437078149529600000)*n^21 + (396094857689/7006757783548723200000)*n^20 + (6679461999989/7006757783548723200000)*n^19 + (547863678243919/38721556172242944000000)*n^18 + (141208125703/778714050723840000)*n^17 + (158554533363656141/65143323913302835200000)*n^16 + (419646908655776387/21714441304434278400000)*n^15 + (34347029867992834633/131837679348350976000000)*n^14 + (1266718500282289837/1014135994987315200000)*n^13 + (9716212166878002126877/606960392999908147200000)*n^12 + (335312354448704163977/9196369590907699200000)*n^11 + (159811684803322290398501/344863859659038720000000)*n^10 + (2084441015987792321011/3831820662878208000000)*n^9 + (534940049155361563279/370301996832768000000)*n^8 - (3741738227767827938821/524594495513088000000)*n^7 + (4617889332661283368409/27501209255520000000)*n^6 - (79303896446545304744351/86311487509632000000)*n^5 + (271428624588728416968929/48622137963759360000)*n^4 - (363488454190223116987/6092999744832000)*n^3 + (113319466669048764966593/279770238283536000)*n^2 - (4480560248750347/3512955600)*n + 1514653 for n>6