cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-1 of 1 results.

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).

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Jan 28 2020

Keywords

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.

Crossrefs

Intersection of A331820 and A331821.

Programs

  • 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
Showing 1-1 of 1 results.