A331086 Positive numbers k such that k and k + 1 are both negaFibonacci-Niven numbers (A331085).

1, 4, 5, 9, 12, 13, 26, 68, 86, 87, 88, 89, 93, 99, 155, 176, 177, 183, 195, 212, 230, 231, 232, 233, 237, 243, 255, 320, 321, 327, 384, 395, 411, 415, 424, 464, 465, 471, 475, 484, 515, 544, 575, 591, 602, 644, 655, 656, 744, 824, 875, 894, 924, 1043, 1115, 1127

Offset

1,2

Comments

Fibonacci numbers F(6*k - 1) and F(6*k) are terms.

Links

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

Mathematica

ind[n_] := Floor[Log[Abs[n]*Sqrt[5] + 1/2]/Log[GoldenRatio]];
f[1] = 1; f[n_] := If[n > 0, i = ind[n - 1]; If[EvenQ[i], i++]; i, i = ind[-n]; If[OddQ[i], i++]; i];
negaFibTermsNum[n_] := Module[{k = n, s = 0}, While[k != 0, i = f[k]; s += 1; k -= Fibonacci[-i]]; s];
negFibQ[n_] := Divisible[n, negaFibTermsNum[n]];
nConsec = 2; neg = negFibQ /@ Range[nConsec]; seq = {}; c = 0; k = nConsec + 1; While[c < 55, If[And @@ neg, c++; AppendTo[seq, k - nConsec]]; neg = Join[Rest[neg], {negFibQ[k]}]; k++]; seq

Crossrefs

Cf. A328209, A328213, A330927, A330931, A331085.

Sequence in context: A047610 A126004 A258251 * A332020 A184801 A228914

Adjacent sequences: A331083 A331084 A331085 * A331087 A331088 A331089

Keyword

nonn,base

Author

Amiram Eldar, Jan 08 2020

Status

approved