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A114735 Least odd number k such that Phi(k,x) is a flat cyclotomic polynomial of order n. 0
3, 15, 231, 431985 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

A flat polynomial is defined to be a polynomial whose coefficients are -1, 0, or 1. Order n means that k is the product of n distinct odd primes. Although the first four numbers are triangular (A000217), this appears to be a coincidence. Are there flat cyclotomic polynomials of all orders?

Conjecture that the next two terms are 746443728915 = 3 * 5 * 31 * 929 * 1727939 and 7800513423460801052132265 = 3 * 5 * 31 * 929 * 1727941 * 10450224300389. [From T. D. Noe (noe(AT)sspectra.com), Apr 13 2010]

CROSSREFS

Cf. A117223 (third-order flat cyclotomic polynomials), A117318 (fourth-order flat cyclotomic polynomials).

Sequence in context: A007081 A126455 A136466 * A173146 A139289 A116518

Adjacent sequences:  A114732 A114733 A114734 * A114736 A114737 A114738

KEYWORD

nonn

AUTHOR

T. D. Noe (noe(AT)sspectra.com), Mar 14 2006

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Last modified February 17 21:13 EST 2012. Contains 206085 sequences.