cp's OEIS Frontend

A232743 Numbers n for which the largest m such that (m-1)! divides n is a composite number > 5.

%I A232743 #11 Dec 05 2013 08:35:49
%S A232743 120,240,360,480,600,840,960,1080,1200,1320,1560,1680,1800,1920,2040,
%T A232743 2280,2400,2520,2640,2760,3000,3120,3240,3360,3480,3720,3840,3960,
%U A232743 4080,4200,4440,4560,4680,4800,4920,5040,5160,5280,5400,5520,5640,5880,6000,6120,6240
%N A232743 Numbers n for which the largest m such that (m-1)! divides n is a composite number > 5.
%C A232743 Numbers n for which A055881(n)>4 and is one of the terms of A072668.
%C A232743 Numbers n for which two plus the number of the trailing zeros in their factorial base representation A007623(n) is a composite number larger than 5.
%C A232743 All terms are multiples of 120. Specifically, these are all those terms of A232742 which are divisible by 120 (or equally: 24).
%C A232743 Please see also the comments in A055926, whose subset this sequence is.
%H A232743 Antti Karttunen, <a href="/A232743/b232743.txt">Table of n, a(n) for n = 1..25920</a>
%e A232743 120 is included because A055881(120)=5 and 5+1 is a composite number larger than 5. Note that A007623(120) = '10000', with four trailing zeros.
%e A232743 720 is the first missing multiple of 120, as A055881(720)=6 and 7 is a prime, not composite, so 720 is not included in this sequence. Note that A007623(720) = '100000', with five trailing zeros, and 5+2 is not a composite.
%e A232743 120960 (= 3*8!) is included because A055881(120960)=8 and 9 is a composite number larger than 5. Note that A007623(120960) = '30000000', with seven trailing zeros.
%o A232743 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A232743 (define A232743 (MATCHING-POS 1 1 (lambda (n) (cond ((A055881 n) => (lambda (k) (and (> k 4) (not (prime? (+ k 1))))))))))
%Y A232743 Subset of both A232742 and A055926.
%Y A232743 Cf. also A007623, A055881, A230403, A232744-A232745.
%K A232743 nonn
%O A232743 1,1
%A A232743 _Antti Karttunen_, Dec 01 2013