A378162 Number k such that !k = A000166(k) is squarefree.

0, 2, 3, 6, 8, 11, 14, 15, 18, 20, 24, 27, 30, 32, 35, 36, 39, 42, 44, 47, 48, 54, 59, 60, 62, 63, 66, 68, 71, 72, 74, 75, 80, 83, 84, 86, 87, 90, 92, 95, 96, 98, 102, 104, 107, 108, 110, 114, 116

Offset: 1

Author

Amiram Eldar, Nov 18 2024

Keywords

• nonn
• more

Comments

0 and numbers k such that A378160(k) = A378161(k).

If k is a term, then k-1 is squarefree (since (k-1) | A000166(k)).

a(34) >= 83.

Crossrefs

Cf. A000166, A005117, A378160, A378161.

Programs

Mathematica

Select[Range[0, 40], SquareFreeQ[Subfactorial[#]] &]

PARI

lista(kmax) = {my(s = 0); print1(0, ", "); for(k = 2, kmax, s = k * s + (-1)^k; if(issquarefree(s), print1(k, ", ")));}

Extensions

a(34)-a(49) from Jinyuan Wang, Nov 25 2024