This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A232741 #13 May 16 2025 02:11:44
%S A232741 1,2,3,4,5,7,8,9,10,11,13,14,15,16,17,19,20,21,22,23,24,25,26,27,28,
%T A232741 29,31,32,33,34,35,37,38,39,40,41,43,44,45,46,47,48,49,50,51,52,53,55,
%U A232741 56,57,58,59,61,62,63,64,65,67,68,69,70,71,72,73,74,75,76
%N A232741 Numbers n for which the largest m such that (m-1)! divides n is a prime.
%C A232741 Numbers n for which A055881(n) is one of the terms of A006093.
%C A232741 Equally: Numbers n for which {the number of the trailing zeros in their factorial base representation A007623(n)} + 2 is a prime.
%C A232741 The sequence can be described in the following manner: Sequence includes all multiples of 1! and 2! (odd and even numbers), except that it excludes from those the multiples of 3! (6), except that it includes the multiples of 4! (24), except that it excludes the multiples of 5! (120), except that it includes the multiples of 6! (720), except that it excludes the multiples of 7! (5040) (and also those of 8! and 9!, because here 8+1 = 9 is the first odd composite), except that it includes the multiples of 10!, but excludes the multiples of 11!, but includes the multiples of 12!, but excludes the multiples of 13! (and also of 14! and 15!, because 14-16 are all composites), but includes the multiples of 16!, and so on, ad infinitum.
%H A232741 Antti Karttunen, <a href="/A232741/b232741.txt">Table of n, a(n) for n = 1..8748</a>
%o A232741 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A232741 (define A232741 (MATCHING-POS 1 1 (lambda (n) (prime? (+ 1 (A055881 n))))))
%Y A232741 Complement: A232742. Cf. A055926, A232744-A232745, A007623, A055881, A230403.
%K A232741 nonn
%O A232741 1,2
%A A232741 _Antti Karttunen_, Dec 01 2013