Empirical: a(n) = (1/48569119454267387884339200000000)*n^36 + (1/179885627608397732904960000000)*n^35 + (431/555578436821588650229760000000)*n^34 + (6667/92512608484318834065408000000)*n^33 + (1274388781/258885120950111698314854400000000)*n^32 + (5917291511/22652448083134773602549760000000)*n^31 + (314124197273/28132879070989960764456960000000)*n^30 + (186928209749/473816910669304602348748800000)*n^29 + (1432318968617963/121955337844685544200601600000000)*n^28 + (3644282905381673/12195533784468554420060160000000)*n^27 + (25093870971913/3820655947515211284480000000)*n^26 + (15725028272797421/125082397789421070974976000000)*n^25 + (3076856865699125479/1459294640876579161374720000000)*n^24 + (89657508109976713/2880186791203774660608000000)*n^23 + (21231596927859607/52291972319992086528000000)*n^22 + (231922603501042141/49439682920719790899200000)*n^21 + (441644639357425688599/9181655399562246881280000000)*n^20 + (33138364242364478551/75613632702277327257600000)*n^19 + (1317727534004662468219849/371168419527303830175744000000)*n^18 + (5061361090965652508734399/197956490414562042760396800000)*n^17 + (192757729610145833605889587/1178312442943821683097600000000)*n^16 + (10257431523517448259202751/11046679152598328279040000000)*n^15 + (2032222827024513176004585353/435554778016734086430720000000)*n^14 + (485303277020066207178394253/23452949585516450807808000000)*n^13 + (14396562568541948754984168943/178446355541972995276800000000)*n^12 + (67536022363649177298276913/245470465159412613120000000)*n^11 + (22177353333915417322540979/27194978647398481920000000)*n^10 + (111114214111787988356542751/53302158148901024563200000)*n^9 + (5003912814450386141011727233/1099196651566876262400000000)*n^8 + (53689467395837493339250658393/6395950516304761251840000000)*n^7 + (220657021904700802874735339807/17134830395532508538880000000)*n^6 + (3268580702297180151436859173/202912465210253390592000000)*n^5 + (117547961980505533781823671/7343498740942503659520000)*n^4 + (2362850305592284762931/192843979541557344000)*n^3 + (4601052076749823081/642435361984416000)*n^2 + (42659368387847/18050444111700)*n + 1