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

1,2

Comments

Sequence is complete. - Giovanni Resta, Mar 21 2013

Links

Table of n, a(n) for n=1..8.

Example

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

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 *)

Crossrefs

Cf. A007661, A014080, A097653, A173574-A173577

Sequence in context: A115901 A073325 A142959 * A037395 A009496 A263281

Adjacent sequences: A173570 A173571 A173572 * A173574 A173575 A173576

Keyword

easy,fini,full,nonn,base

Author

Paolo P. Lava and Giorgio Balzarotti, Feb 22 2010

Status

approved