A173574 4-Factorions: equal to the sum of the quadruple factorials of their digits in base 10.

1, 2, 3, 4, 5, 49

Offset

1,2

Links

Table of n, a(n) for n=1..6.

Example

49 -> 4!!!! + 9!!!! = 4 + 9*5 = 4 +45 = 49.

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, 4);

Mathematica

qfd[n_]:=Times@@Range[n, 1, -4]; Select[Range[50], Total[qfd/@ IntegerDigits[ #]] == #&] (* Harvey P. Dale, Dec 15 2018 *)

Crossrefs

Cf. A007662, A014080, A097653, A173573, A173575-A173577

Sequence in context: A028427 A037329 A344848 * A278940 A273470 A303163

Adjacent sequences: A173571 A173572 A173573 * A173575 A173576 A173577

Keyword

easy,fini,nonn,base

Author

Paolo P. Lava, Feb 22 2010

Status

approved