A331830 Numbers k such that k and k + 1 are both negabinary evil numbers.

7, 13, 19, 27, 31, 39, 45, 51, 55, 61, 67, 75, 79, 87, 93, 99, 107, 111, 117, 123, 127, 135, 141, 147, 155, 159, 167, 173, 179, 183, 189, 195, 203, 207, 213, 219, 223, 231, 237, 243, 247, 253, 259, 267, 271, 279, 285, 291, 299, 303, 309, 315, 319, 327, 333, 339

Offset: 1

Author

Amiram Eldar, Jan 28 2020

Keywords

• nonn
• base

Examples

			7 is a term since both 7 and 7 + 1 = 8 are negabinary evil numbers (A268272): 7 has 4 digits of 1 in its negabinary representation, 11011, 8 has 2 digits of 1 in its negabinary representation, 11000, and both 4 and 2 are even.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A157970, A268272, A331831.

Programs

Mathematica

negaBinWt[n_] := negaBinWt[n] = If[n==0, 0, negaBinWt[Quotient[n-1, -2]] + Mod[n, 2]]; evilNegaBinQ[n_] := EvenQ[negaBinWt[n]]; c = 0; k = 1; s = {}; v = Table[-1, {2}]; While[c < 60, If[evilNegaBinQ[k], v = Join[Rest[v], {k}]; If[AllTrue[Differences[v], # == 1 &], c++; AppendTo[s, k - 1]]]; k++]; s