%I #7 Jun 09 2023 23:18:53
%S 1,2,12,840,1663200,174356582400,1561112121913344000,
%T 1754317855900734514790400000,341362923889542287855059017400320000000,
%U 15163751542692044063740921044974247390216192000000000,195932150519417838363658963697014150610807423633478962380800000000000
%N a(n) = (n*(n+1)/2+1)!/n!.
%t Table[(n (n+1)/2+1)!/n!,{n,0,20}] (* _Harvey P. Dale_, Aug 04 2022 *)
%Y Cf. A000124, A107868, A129893.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Jun 06 2007