A331206 Numbers k such that A053985(k) divides k.

1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 17, 20, 21, 24, 30, 32, 34, 40, 42, 48, 51, 60, 63, 64, 65, 68, 69, 80, 81, 84, 85, 96, 102, 120, 126, 128, 130, 136, 138, 160, 162, 168, 170, 192, 195, 204, 207, 240, 243, 252, 255, 256, 257, 260, 261, 272, 273, 276, 277

Offset: 1

Author

Alon Ran, Jan 12 2020

Keywords

• nonn
• base

Comments

It appears that A053985(a(n)) / a(n) is always either 1, -1, 3 or -3.

This sequence seems to contain A329000.

Examples

			15 is written 1111 base 2 and (-2)^3 + (-2)^2 + (-2)^1 +(-2)^0 = -8 + 4 - 2 + 1 = -5, 15 is divisible by -5.
		

Programs

PARI

is(k) = k%fromdigits(binary(k), -2) == 0; \\ Jinyuan Wang, Jan 15 2020