A173573 3-Factorions: equal to the sum of the triple factorials of their digits in base 10.

1, 2, 3, 4, 81, 82, 83, 84

Offset: 1

Author

Paolo P. Lava and Giorgio Balzarotti, Feb 22 2010

Keywords

• easy
• fini
• full
• nonn
• base

Comments

Sequence is complete. - Giovanni Resta, Mar 21 2013

Examples

			81 -> 8!!! + 1!!! = 8*5*2 + 1 = 80 + 1 = 81.
		

Crossrefs

Cf. A007661, A014080, A097653, A173574-A173577

Programs

Maple

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(1000,3);

Mathematica

stfQ[n_]:=n==Total[Times@@Range[#,1,-3]&/@IntegerDigits[n]]; Select[Range[100],stfQ] (* Harvey P. Dale, May 31 2023 *)