Empirical: a(n) = (1/8222838654177922817725562880000000)*n^31 + (1/16578303738261941164769280000000)*n^30 + (1/69803384161102910167449600000)*n^29 + (283/130666433405020225929216000000)*n^28 + (12737/54444347252091760803840000000)*n^27 + (1395431/72592463002789014405120000000)*n^26 + (2930383/2345294958551645080780800000)*n^25 + (309433871/4690589917103290161561600000)*n^24 + (6146257939/2132086325956040982528000000)*n^23 + (107668553/1018674785454391296000000)*n^22 + (1063169059/323712209599951011840000)*n^21 + (846152299411/9711366287998530355200000)*n^20 + (821810531233889/414250468222437310464000000)*n^19 + (27143401299834577/697684999111473364992000000)*n^18 + (9189036143501857/13953699982229467299840000)*n^17 + (11291471241817787/1172579830439451033600000)*n^16 + (8078015556597795617/66446190391568891904000000)*n^15 + (43905435176059709321/33223095195784445952000000)*n^14 + (13677769365754845133/1112392865716195295232000)*n^13 + (1347774715072715355071/13904910821452441190400000)*n^12 + (64155564386515407955111/100627644102616350720000000)*n^11 + (35984911574855557208177/10505083724998410240000000)*n^10 + (306200874598059060317111/20940133558496831078400000)*n^9 + (278306506643473668576253/5816703766249119744000000)*n^8 + (25289086748280653986446587/220550017803612456960000000)*n^7 + (3641713638350578025580091/18379168150301038080000000)*n^6 + (6838336252549512410863/20421297944778931200000)*n^5 + (184908847072223416781/218799620836917120000)*n^4 + (49703260347907723/28028929252896000)*n^3 + (157340267053201/82576811772000)*n^2 + (14288757019/18753708168)*n