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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.
0
29, 11, 41, 71, 17, 23, 53, 23, 131, 41, 307, 509, 61, 181, 37, 191, 41, 229, 239, 89, 47, 797, 73, 571, 499, 157, 59, 643, 73, 71, 739, 373, 71, 607, 359, 419, 83, 431, 433, 89, 443, 941, 83, 1481, 109, 251, 1553, 1061, 101, 1721, 101, 401, 599, 251, 131
OFFSET
1,1
COMMENTS
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.
LINKS
Nathan Kaplan, Flat cyclotomic polynomials of order three, J. Number Theory 127 (2007), 118-126.
EXAMPLE
a(1)=29 because 15*29 is the least multiple of 15 that produces a flat cyclotomic polynomial.
CROSSREFS
Sequence in context: A070714 A040816 A336061 * A332940 A165769 A040815
KEYWORD
nonn
AUTHOR
T. D. Noe, May 15 2009
STATUS
approved