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A066419 Numbers k such that k! is not divisible by the sum of the decimal digits of k!. 1

%I #28 Jun 14 2021 16:07:01

%S 432,444,453,458,474,476,485,489,498,507,509,532,539,541,548,550,552,

%T 554,555,556,560,565,567,576,593,597,603,608,609,610,611,612,613,624,

%U 630,632,634,640,645,657,663,665,683,685,686,692,698,703,706,708,714

%N Numbers k such that k! is not divisible by the sum of the decimal digits of k!.

%H Michael S. Branicky, <a href="/A066419/b066419.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Matthew Conroy)

%e The sum of the decimal digits of 5! is 1+2+0=3 and 3 divides 120, so 5 is not in the sequence.

%e The sum of the decimal digits of 432! is 3897 = (9)(433) and 3897 does not divide 432!, so 432 is in the sequence.

%t Select[Range[1000], !Divisible[Factorial[#],Total[IntegerDigits[Factorial[#]]]] &], (* _Tanya Khovanova_, Jun 13 2021 *)

%o (Python)

%o from math import factorial

%o def sd(n): return sum(map(int, str(n)))

%o def ok(f): return f%sd(f) != 0

%o print([n for n in range(1, 715) if ok(factorial(n))]) # _Michael S. Branicky_, Jun 13 2021

%K base,easy,nonn

%O 1,1

%A _Matthew Conroy_, Dec 25 2001

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Last modified April 25 16:45 EDT 2024. Contains 371989 sequences. (Running on oeis4.)