A389917 Odd numbers m such that the Stern polynomial B(m,x) is reducible.

9, 15, 21, 27, 33, 35, 39, 45, 49, 51, 57, 63, 69, 75, 81, 85, 87, 93, 99, 105, 111, 117, 119, 123, 129, 135, 141, 147, 153, 155, 159, 165, 171, 177, 183, 187, 189, 195, 201, 207, 213, 217, 219, 221, 225, 231, 237, 243, 249, 255, 259, 261, 267, 273, 275, 279, 285, 287, 291, 297, 303, 309, 315, 321, 325, 327, 333

Offset

1,1

Comments

Ulas & Ulas conjecture implies that there should be only composite terms in this sequence. See A186891.

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Prog

(PARI)
ps(n) = if(n<2, n, if(n%2, ps(n\2)+ps(n\2+1), 'x*ps(n\2)));
A283991(n) = polisirreducible(ps(n));
is_A389917(k) = (k > 1 && k%2 && !A283991(k));

Crossrefs

Odd terms of A389916.

Conjectured to be a subsequence of A071904.

Cf. A186891, A186892, A283991, A389915 (subsequence).

Sequence in context: A139787 A372080 A225461 * A172181 A063139 A392494

Adjacent sequences: A389914 A389915 A389916 * A389918 A389919 A389920

Keyword

nonn

Author

Antti Karttunen, Dec 03 2025

Status

approved