A331820 Positive numbers k such that k and k + 1 are both negabinary-Niven numbers (A331728).

1, 2, 3, 8, 14, 15, 20, 32, 35, 56, 62, 63, 68, 80, 90, 95, 124, 125, 128, 174, 184, 185, 215, 224, 244, 245, 248, 254, 255, 260, 272, 275, 300, 304, 305, 320, 335, 342, 468, 469, 484, 485, 512, 515, 544, 545, 552, 575, 594, 636, 720, 762, 784, 785, 804, 846, 896

Offset: 1

Author

Amiram Eldar, Jan 27 2020

Keywords

• nonn
• base

Examples

			8 is a term since both 8 and 8 + 1 = 9 are negabinary-Niven numbers: A039724(8) = 11000 and 1 + 1 + 0 + 0 + 0 = 2 is a divisor of 8, and A039724(9) = 11001 and 1 + 1 + 0 + 0 + 1 = 3 is a divisor of 9.
		

Links

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

Crossrefs

Cf. A027615, A039724, A328209, A328213, A330927, A330931, A331086, A331089, A331728.

Programs

Mathematica

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