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%I #10 Dec 15 2017 17:36:09
%S 1,1,0,4,21,169,1504,15755,177333,213789
%N Number of times n appears among the decimal digits of (n!)!.
%e a(4)=4 because 4 appears four times in (4!)! = 620448401733239439360000.
%t Table[Count[Partition[IntegerDigits[(n!)!],IntegerLength[n],1], IntegerDigits[ n]],{n,10}] (* _Harvey P. Dale_, May 19 2014 *)
%t Table[SequenceCount[IntegerDigits[(n!)!],IntegerDigits[n]],{n,10}] (* The program uses the SequenceCount function from Mathematica version 10 *) (* _Harvey P. Dale_, Aug 08 2016 *)
%o (PARI) {mdcp(d,n)=local(a, c=0,L); L=length(Str(d)); if(L>1,a=2,a=1); while(n>0,if(n%(10^a)==d,n=floor(n/10); c++,n=floor(n/10); )); c } for(n=1,10,print1(mdcp(n,n!!)","))
%Y Cf. A000197.
%K base,more,nonn
%O 1,4
%A _Jason Earls_, Dec 16 2002
%E Added a(9) and a(10). - Ryan Leonel (ryan.leonel(AT)gmail.com), Oct 03 2008
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