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 A075795 #37 Feb 16 2025 08:32:47
%S A075795 0,0,1,1,3,3,5,4,6,7,9,8,11,11,12,11,15,14,17,16,18,19,21,19,22,23,23,
%T A075795 24,27,26,29,26,30,31,32,31,35,35,36,35,39,38,41,40,41,43,45,42,46,46,
%U A075795 48,48,51,49,52,51,54,55,57,55,59,59,59,57,62,62,65,64,66,66,69,66,71
%N A075795 Number of k, 0<k<=n, such that the resultant of the k-th cyclotomic polynomial and the n-th cyclotomic polynomial is equal to 1.
%C A075795 a(n) >= A000010(n)-1 since if 2<=k<n and (k,n)=1, the resultant is 1. - corrected by _Robert Israel_, Jul 24 2016
%C A075795 For n>1 a(n) = number of roots of the n-th polynomial in A275345, equal to 1. - _Mats Granvik_, Jul 24 2016
%H A075795 Robert Israel, <a href="/A075795/b075795.txt">Table of n, a(n) for n = 1..10000</a>
%H A075795 T. M. Apostol, <a href="http://dx.doi.org/10.1090/S0002-9939-1970-0251010-X">Resultants of Cyclotomic Polynomials</a>, Proc. Amer. Math. Soc. 24, 457-462, 1970.
%H A075795 T. M. Apostol, <a href="http://www.jstor.org/stable/2005456">The Resultant of the Cyclotomic Polynomials Fm(ax) and Fn(bx)</a>, Math. Comput. 29, 1-6, 1975.
%H A075795 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CyclotomicPolynomial.html">Cyclotomic polynomials</a>.
%F A075795 a(n) = n - A073093(n).
%F A075795 a(n) = n - A001222(n) - 1. - _Michel Marcus_, Jul 24 2016
%p A075795 seq(n -numtheory:-bigomega(n)-1, n=1..1000); # _Robert Israel_, Jul 25 2016
%t A075795 Table[n - PrimeOmega@ n - 1, {n, 73}] (* _Michael De Vlieger_, Jul 26 2016 *)
%o A075795 (PARI) a(n)=sum(k=1,n,if(1-polresultant(polcyclo(n),polcyclo(k)),0,1))
%Y A075795 Cf. A001222, A054372, A073093.
%K A075795 nonn
%O A075795 1,5
%A A075795 _Benoit Cloitre_, Oct 13 2002
%E A075795 a(30)=2 and a(31)=6 merged into a(30)=26 by _Mats Granvik_, Jul 24 2016