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 A355475 #20 Jul 28 2024 10:07:58 %S A355475 2,6,12,30,60,120,210,240,420,840,1260,1680,2310,4620,9240,13860, %T A355475 18480,30030,60060,120120,180180,240240,360360,510510,1021020,2042040, %U A355475 3063060,4084080,6126120,8168160,9699690,12252240,19399380,38798760,58198140,77597520 %N A355475 Numbers that are sparsely totient (A036913) and of least prime signature (A025487). %C A355475 All sparsely totient numbers are even, but not all sparsely totient numbers have least prime signature. %C A355475 The present sequence is infinite, as it includes all primorials greater than one (A002110); see Masser and Shiu for proof. %H A355475 Amiram Eldar, <a href="/A355475/b355475.txt">Table of n, a(n) for n = 1..141</a> (terms 1..82 from Hal M. Switkay) %H A355475 D. W. Masser and P. Shiu, <a href="https://projecteuclid.org/journals/pacific-journal-of-mathematics/volume-121/issue-2/On-sparsely-totient-numbers/pjm/1102702441.full">On sparsely totient numbers</a>, Pacific J. Math. 121, no. 2 (1986), 407-426. %e A355475 The totient of 18 is 6, which is smaller than the totient of all larger natural numbers; but 18 does not have least prime signature, so it is not a term of this sequence. %e A355475 The totient of 30 is 8, which is smaller than the totient of all larger natural numbers; since 30 has least prime signature, it is a term of this sequence. %Y A355475 Cf. A002110, A025487, A036913. %K A355475 nonn %O A355475 1,1 %A A355475 _Hal M. Switkay_, Jul 03 2022