A331831 - OEIS

A331831

Numbers k such that k and k + 1 are both negabinary odious numbers.

3, 11, 15, 23, 29, 35, 43, 47, 53, 59, 63, 71, 77, 83, 91, 95, 103, 109, 115, 119, 125, 131, 139, 143, 151, 157, 163, 171, 175, 181, 187, 191, 199, 205, 211, 215, 221, 227, 235, 239, 245, 251, 255, 263, 269, 275, 283, 287, 295, 301, 307, 311, 317, 323, 331, 335

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

EXAMPLE

3 is a term since both 3 and 3 + 1 = 4 are negabinary odious numbers (A268273): 3 has 3 digits of 1 in its negabinary representation, 111, 4 has 1 digit of 1 in its negabinary representation, 100, and both 3 and 1 are odd.

MATHEMATICA

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

CROSSREFS

Cf. A157971, A268273, A331830.

Sequence in context: A032466 A060698 A294690 * A357440 A186302 A323103

Adjacent sequences: A331828 A331829 A331830 * A331832 A331833 A331834

KEYWORD

nonn,base

AUTHOR

Amiram Eldar, Jan 28 2020

STATUS

approved