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%I #5 Dec 15 2018 15:42:20
%S 1,2,3,4,5,49
%N 4-Factorions: equal to the sum of the quadruple factorials of their digits in base 10.
%e 49 -> 4!!!! + 9!!!! = 4 + 9*5 = 4 +45 = 49.
%p P:=proc(n,m) local a,b,i,j,k,x,w; for i from 1 by 1 to n do a:=0; b:=0; w:=0; k:=i; while k>0 do w:=k-(trunc(k/10)*10); j:=w; x:=w-m; if w=0 then b:=1; else while x>0 do j:=j*x; x:=x-m; od; b:=j; fi; a:=a+b; k:=trunc(k/10); od; if a=i then lprint(i,a); fi; od; end: P(1000,4);
%t qfd[n_]:=Times@@Range[n,1,-4]; Select[Range[50],Total[qfd/@ IntegerDigits[ #]] == #&] (* _Harvey P. Dale_, Dec 15 2018 *)
%Y Cf. A007662, A014080, A097653, A173573, A173575-A173577
%K easy,fini,nonn,base
%O 1,2
%A _Paolo P. Lava_, Feb 22 2010
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