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A186891 Numbers n such that the Stern polynomial B(n,x) is irreducible. 30
1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 37, 41, 43, 47, 53, 55, 59, 61, 65, 67, 71, 73, 77, 79, 83, 89, 91, 95, 97, 101, 103, 107, 109, 113, 115, 121, 125, 127, 131, 133, 137, 139, 143, 145, 149, 151, 157, 161, 163, 167, 169, 173, 175, 179, 181, 185, 191, 193, 197, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Ulas and Ulas conjecture that all primes are here. The nonprime n are in A186892. See A186886 for the least number having n prime factors.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

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

FORMULA

From Antti Karttunen, Mar 21 2017: (Start)

A283992(a(1+n)) = n.

A260443(a(1+n)) = A277318(n).

(End)

MATHEMATICA

ps[n_] := ps[n] = If[n<2, n, If[OddQ[n], ps[Quotient[n, 2]] + ps[Quotient[n, 2] + 1], x ps[Quotient[n, 2]]]];

selQ[n_] := IrreduciblePolynomialQ[ps[n]];

Join[{1}, Select[Range[200], selQ]] (* Jean-Fran├žois Alcover, Nov 02 2018, translated from PARI *)

PROG

(PARI) ps(n)=if(n<2, n, if(n%2, ps(n\2)+ps(n\2+1), 'x*ps(n\2)))

is(n)=polisirreducible(ps(n)) \\ Charles R Greathouse IV, Apr 07 2015

CROSSREFS

Cf. A057526 (degree of Stern polynomials), A125184, A260443 (Stern polynomials).

Cf. A186892 (subsequence of nonprime terms).

Cf. A186893 (subsequence for self-reciprocal polynomials).

Positions of 0 and 1's in A277013, Positions of 1 and 2's in A284011.

Cf. A283991 (characteristic function for terms > 1).

Cf. also A186886, A277190, A277318, A283992.

Sequence in context: A161578 A261271 A308966 * A206074 A325559 A257688

Adjacent sequences:  A186888 A186889 A186890 * A186892 A186893 A186894

KEYWORD

nonn

AUTHOR

T. D. Noe, Feb 28 2011

STATUS

approved

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Last modified October 14 15:14 EDT 2019. Contains 328019 sequences. (Running on oeis4.)