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 A160494 #7 Apr 14 2017 03:00:13 %S A160494 29,11,41,71,17,23,53,23,131,41,307,509,61,181,37,191,41,229,239,89, %T A160494 47,797,73,571,499,157,59,643,73,71,739,373,71,607,359,419,83,431,433, %U A160494 89,443,941,83,1481,109,251,1553,1061,101,1721,101,401,599,251,131 %N A160494 Least prime r > q such that the third-order cyclotomic polynomial Phi(pqr,x) is flat with p,q,r distinct odd primes, ordered by pq. %C A160494 A flat polynomial is defined to be a polynomial whose coefficients are -1, 0, or 1. Sequence A046388 gives the product pq. As proved by Kaplan, given odd primes p < q, it is always possible to find a prime r > q such that Phi(pqr,x) is flat. %H A160494 Nathan Kaplan, <a href="https://doi.org/10.1016/j.jnt.2007.01.008">Flat cyclotomic polynomials of order three</a>, J. Number Theory 127 (2007), 118-126. %e A160494 a(1)=29 because 15*29 is the least multiple of 15 that produces a flat cyclotomic polynomial. %Y A160494 Cf. A046388, A117223. %K A160494 nonn %O A160494 1,1 %A A160494 _T. D. Noe_, May 15 2009