A115170 - OEIS

A115170

Non-cubefree numbers n such that 2n+1 is also non-cubefree (A046099).

40, 256, 312, 472, 688, 904, 1120, 1200, 1312, 1336, 1552, 1768, 1984, 2187, 2200, 2312, 2416, 2456, 2632, 2848, 2875, 3064, 3280, 3312, 3429, 3496, 3712, 3928, 3944, 4144, 4312, 4360, 4576, 4792, 5008, 5224, 5312, 5440, 5562, 5656, 5872, 6088, 6250, 6304, 6312, 6345, 6520, 6655, 6688, 6736, 6952

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

The probability that a random integer is cubefree is 1/zeta(3) (see A088453).

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..700

EXAMPLE

312 is there because 2^3 divides 312 and 5^3 divides 312*2+1.

CROSSREFS

Cf. A005384 (n and 2n+1 prime), A046099, A088453, A111153 (n and 2n+1 semiprime), A117204 (n and 2n+1 squarefree), A115228.

Sequence in context: A229632 A223426 A290127 * A374240 A247406 A229588