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 A373140 #10 Jul 15 2024 15:32:53
%S A373140 1,7,11,13,17,18,19,23,24,29,31,32,37,41,43,45,47,49,53,59,60,61,67,
%T A373140 71,73,77,79,80,83,89,91,97,101,103,107,109,113,119,121,126,127,131,
%U A373140 133,137,139,143,149,150,151,157,161,163,167,168,169,173,179,181,187,191,193,197,198,199,200,203,209,211,217,221
%N A373140 Numbers k such that A276085(k) is a multiple of 5, where A276085 is the primorial base log-function.
%C A373140 Because A276085 is completely additive, this is a multiplicative semigroup; if m and n are in the sequence then so is m*n.
%C A373140 This looks likely to be the integers in the multiplicative subgroup of the positive rationals generated by 32, 24, 80 and primes greater than 5. - _Peter Munn_, Jul 15 2024
%H A373140 Antti Karttunen, <a href="/A373140/b373140.txt">Table of n, a(n) for n = 1..10000</a>
%o A373140 (PARI)
%o A373140 A002110(n) = prod(i=1,n,prime(i));
%o A373140 A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };
%o A373140 A373139(n) = !(A276085(n)%5);
%Y A373140 Cf. A002110, A276085, A373139 (characteristic function).
%K A373140 nonn
%O A373140 1,2
%A A373140 _Antti Karttunen_, May 26 2024