Apply partial sum operator thrice to factorials.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =11a(6) =28a(7) =79a(8) =284a(9) =1363a(10) =8356a(11) =61583a(12) =523924a(13) =5024179a(14) =53479148a(15) =624890431a(16) =7946278828a(17) =109195935539