login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A331086 Positive numbers k such that k and k + 1 are both negaFibonacci-Niven numbers (A331085). 7
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 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 28 17:15 EDT 2021. Contains 346335 sequences. (Running on oeis4.)