A375497 Numbers k such that 16*k^4 - 1 is squarefree.

1, 2, 3, 6, 7, 8, 10, 11, 15, 17, 18, 20, 21, 26, 27, 28, 29, 30, 33, 36, 39, 42, 43, 44, 45, 46, 47, 48, 51, 52, 53, 54, 55, 56, 57, 64, 65, 69, 70, 71, 72, 75, 78, 79, 80, 81, 82, 83, 89, 90, 92, 93, 96, 97, 98, 99, 100, 101, 102, 105, 106, 107, 108, 110, 111, 114, 115, 117, 118, 119, 120

Offset: 1

Author

Juri-Stepan Gerasimov, Aug 18 2024

Keywords

• nonn

Crossrefs

Cf. A005117, A016744.

Programs

Magma

[k: k in [1..120] | IsSquarefree(16*k^4-1)];

Maple

select(k -> numtheory:-issqrfree(16*k^4-1), [$1..200]); # Robert Israel, Aug 18 2024

Mathematica

Select[Range[120], SquareFreeQ[16 * #^4 - 1] &] (* Amiram Eldar, Aug 18 2024 *)

PARI

isok(k) = issquarefree(16*k^4 - 1); \\ Michel Marcus, Aug 18 2024