Empirical: a(n) = (1/265252859812191058636308480000000)*n^30 + (1/609776689223427721003008000000)*n^29 + (37/107607651039428421353472000000)*n^28 + (73/1583835556424487587020800000)*n^27 + (642907/145184926005578028810240000000)*n^26 + (3833/11818064794918846464000000)*n^25 + (176502499/9381179834206580323123200000)*n^24 + (554570147/625411988947105354874880000)*n^23 + (70483840991/2039386920479691374592000000)*n^22 + (21892489/19403329246750310400000)*n^21 + (604862306759/19422732575997060710400000)*n^20 + (294963971/403003062060318720000)*n^19 + (20553393791236469/1395369998222946729984000000)*n^18 + (431281195618579/1691357573603571793920000)*n^17 + (62565269960619241/16416117626152314470400000)*n^16 + (7052010074610703/156343977391926804480000)*n^15 + (9332767373960809003/16611547597892222976000000)*n^14 + (4389741455496653/1014135994987315200000)*n^13 + (3299787980310141337/70291369042268774400000)*n^12 + (9176303061773633183/46349702738174803968000)*n^11 + (246399543003676446913369/119495327371856916480000000)*n^10 + (293418218837824057051/87542364374986752000000)*n^9 + (163215529639524000037313/2908351883124559872000000)*n^8 - (93648173737728901589/2518053578462822400000)*n^7 + (28175327215048179123962177/36758336300602076160000000)*n^6 - (296257031283177709916077/612638938343367936000000)*n^5 + (30408826732831281319847/6126389383433679360000)*n^4 - (732158674724758153/107254716096528000)*n^3 + (4815318254084760923/279770238283536000)*n^2 - (454287633551/80313433200)*n + 1