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 A070518 #25 Feb 16 2025 08:32:46
%S A070518 0,3,13,17,781,31,137257,4097,532171,9091,28531167061,20593,
%T A070518 25239592216021,7027567,2392743361,4294967297,51702516367896047761,
%U A070518 34006393,109912203092239643840221,25536159601,7006306553612521,25405143539623,949112181811268728834319677753
%N A070518 Value of n-th cyclotomic polynomial at n.
%C A070518 a(28341) is divisible by 283411^2. What is the next n such that a(n) is not squarefree? - _Jianing Song_, Nov 01 2024
%H A070518 G. C. Greubel, <a href="/A070518/b070518.txt">Table of n, a(n) for n = 1..250</a>
%H A070518 Mathematics Stack Exchange, <a href="https://math.stackexchange.com/q/3986249">Is the "cyclotomic diagonalization" always squarefree?</a>
%H A070518 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CyclotomicPolynomial.html">Cyclotomic Polynomial</a>
%e A070518 n=10: 10th cyclotomic polynomial is 1-x+x^2-x^3+x^4; at x=10 it gives a(10)=9091.
%p A070518 a:= n-> numtheory[cyclotomic](n$2):
%p A070518 seq(a(n), n=1..25); # _Alois P. Heinz_, Jul 05 2024
%t A070518 Table[Cyclotomic[w, w], {w, 1, 35}]
%o A070518 (PARI) a(n) = polcyclo(n, n) \\ _Michel Marcus_, Apr 02 2016
%Y A070518 Cf. A070519 (indices of prime terms), A088790 (prime indices of prime terms).
%K A070518 nonn
%O A070518 1,2
%A A070518 _Labos Elemer_, May 02 2002