A358848 Numbers k for which A053669(6*k) [the smallest prime not dividing 6k] is of the form 6m+1.

5, 10, 15, 20, 25, 30, 40, 45, 50, 55, 60, 65, 75, 80, 85, 90, 95, 100, 110, 115, 120, 125, 130, 135, 145, 150, 155, 160, 165, 170, 180, 185, 190, 195, 200, 205, 215, 220, 225, 230, 235, 240, 250, 255, 260, 265, 270, 275, 285, 290, 295, 300, 305, 310, 320, 325, 330, 335, 340, 345, 355, 360, 365, 370, 375, 380, 385

Offset

1,1

Comments

Contains only multiples of 5. Differs from A067761 by including for example 385 = 5*7*11, which is not present in A067761.

The asymptotic density of this sequence is 6 * Sum_{p prime, p == 1 (mod 6)} ((p-1)/(Product_{q prime, q <= p} q)) = 0.1738373091... . - Amiram Eldar, Dec 04 2022

Links

Table of n, a(n) for n=1..67.

Formula

{k | A053669(6*k) == 1 (mod 6)}.

Example

35 is not present as 6*35 = 210 = 2*3*5*7, and the first nondividing prime is 11, which is of the form 6m+5, not of 6m+1.
385 is present as 6*385 = 2310 = 2*3*5*7*11, and the first nondividing prime is 13, which is of the form 6m+1.

Mathematica

f[n_] := Module[{p = 2}, While[Divisible[n, p], p = NextPrime[p]]; p]; Select[Range[400], Mod[f[6*#], 6] == 1 &] (* Amiram Eldar, Dec 04 2022 *)

Prog

(PARI) isA358848(n) = !A358847(n);

Crossrefs

Positions of 0's in A358847. Complement is A358849. Subsequence of A008587.

Not the same as A067761.

Cf. A053669.

Sequence in context: A292656 A313735 A067761 * A080193 A313736 A313737

Adjacent sequences: A358845 A358846 A358847 * A358849 A358850 A358851

Keyword

nonn

Author

Antti Karttunen, Dec 03 2022

Status

approved