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A186886 Least number k having exactly n prime divisors and the Stern polynomial B(k,x) is irreducible. 1
2, 55, 665, 6545, 85085, 1616615, 37182145 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Ulas and Ulas tabulate these values and conjecture 6.5, p.20, that a(n) exists for all n.

See A125184 for the Stern polynomials. See A186891 for n such that the Stern polynomial B_n(x) is irreducible.

LINKS

Table of n, a(n) for n=1..7.

Maciej Ulas and Oliwia Ulas, On certain arithmetic properties of Stern polynomials, arXiv:1102.5109 [math.CO], 2011.

EXAMPLE

a(1) = 2.

a(2) = 55 = 5 * 11.

a(3) = 665 = 5 * 7 * 19.

a(4) = 6545 = 5 * 7 * 11 * 17.

a(5) = 85085 = 5 * 7 * 11 * 13 * 17.

a(6) = 1616615 = 5 * 7 * 11 * 13 * 17 * 19.

a(7) = 37182145 = 5 * 7 * 11 * 13 * 17 * 19 * 23.

CROSSREFS

Cf. A125184, A186891.

Sequence in context: A157262 A007975 A109796 * A024029 A134501 A210928

Adjacent sequences:  A186883 A186884 A186885 * A186887 A186888 A186889

KEYWORD

nonn,more

AUTHOR

Jonathan Vos Post, Feb 28 2011

STATUS

approved

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Last modified December 12 12:30 EST 2019. Contains 329958 sequences. (Running on oeis4.)