A074257 Sum of factorials of digits of n equals the largest prime factor of n.

2, 12, 341, 403, 1200, 1232, 2000, 2204, 4530, 4614, 5134, 10000, 13200, 13345, 14210, 21141, 23100, 31433, 40020, 101442, 111252, 111452, 112000, 112320, 123201, 135453, 145343, 162121, 173434, 200025, 202106, 203050, 210000, 211420

Offset: 1

Author

Jason Earls, Sep 20 2002

Keywords

• base
• nonn

Examples

			4614 = 2*3*769 and 4!+6!+1!+4! = 769.
		

Links

• Vincenzo Librandi and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 250 terms from Librandi)

Crossrefs

Cf. A061602.

Programs

Mathematica

Select[Range[220000],FactorInteger[#][[-1,1]]==Total[IntegerDigits[#]!]&] (* Harvey P. Dale, Mar 08 2014 *)

PARI

gpf(n)=if(n<2,1,my(f=factor(n)[,1]);f[#f])
is(n)=my(d=digits(n),t=sum(i=1,#d,d[i]!));n%t==0&&isprime(t)&&gpf(n/t)<=t \\ Charles R Greathouse IV, Mar 10 2014