Partial sums of A001378.

Terms

a(0) =1a(1) =4372a(2) =100627a(3) =1240001a(4) =10698751a(5) =20249386a(6) =83781871a(7) =431424985a(8) =787479360a(9) =2194606250a(10) =5409349991a(11) =9630730661a(12) =13906093181a(13) =18529006931a(14) =27816044405a(15) =40317825620a(16) =53826243764a(17) =81242430639a(18) =157086570010a(19) =237512970010