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%I #12 Aug 18 2019 01:44:16
%S 11,11,21,61,241,1201,7201,50401,403201,36288001,362880001,3991680001,
%T 47900160001,622702080001,8717829120001,130767436800001,
%U 2092278988800001,35568742809600001,640237370572800001
%N n! concatenated with n divided by n.
%F (n-1)! followed by a 1.
%e a(14) = 622702080001: 14! concatenated with 14 is 8717829120014 and 87178291200/14 = 622702080001.
%p c:=proc(x,y) local s: s:=proc(m) nops(convert(m,base,10)) end: x*10^s(y)+y: end: a:=n->c(n!,n)/n: seq(a(n),n=1..22); # c yields the concatenation of two positive integers # _Emeric Deutsch_, Aug 07 2005
%t Table[(n!*10^IntegerLength[n]+n)/n,{n,20}] (* _Harvey P. Dale_, Sep 10 2016 *)
%o (PARI) a(n) = fromdigits(concat(digits(n!), digits(n)))/n; \\ _Michel Marcus_, Aug 18 2019
%Y Cf. A110415.
%K base,easy,nonn
%O 1,1
%A _Amarnath Murthy_, Aug 01 2005
%E More terms from _Emeric Deutsch_ and _Erich Friedman_, Aug 07 2005