A331829 Positive numbers k such that k and k + 1 are both positive negabinary-Niven numbers (A331728) and -k and -(k + 1) are both negative negabinary-Niven numbers (A331819).

2, 3, 8, 15, 32, 63, 128, 174, 245, 255, 512, 1023, 1085, 1295, 1505, 1854, 1925, 2048, 2744, 3248, 3303, 3752, 4025, 4095, 4760, 4815, 4865, 5004, 5319, 5768, 6327, 6776, 7104, 7784, 7944, 8154, 8192, 8574, 8792, 8855, 9800, 10254, 10808, 11312, 11816, 11871

Offset

1,1

Comments

Positive numbers k such that both k and k + 1 are in A331827.

Numbers of the form 2^(2*k+1) and 2^(2*k) - 1 are terms.

Links

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

Mathematica

negaBinWt[n_] := negaBinWt[n] = If[n==0, 0, negaBinWt[Quotient[n-1, -2]] + Mod[n, 2]]; negBinQ[n_] := And @@ (Divisible[n, negaBinWt[#]] & /@ {-n, n}); nConsec = 2; neg = negBinQ /@ Range[nConsec]; seq = {}; c = 0; k = nConsec + 1; While[c < 45, If[And @@ neg, c++; AppendTo[seq, k - nConsec]]; neg = Join[Rest[neg], {negBinQ[k]}]; k++]; seq

Crossrefs

Intersection of A331820 and A331821.

Cf. A331092, A331728, A331819, A331827.

Sequence in context: A128022 A011946 A195095 * A166920 A242510 A080206

Adjacent sequences: A331826 A331827 A331828 * A331830 A331831 A331832

Keyword

nonn,base

Author

Amiram Eldar, Jan 28 2020

Status

approved