A083094 Numbers k such that Sum_{j=0..k} (binomial(k,j) mod 3) is odd.

0, 8, 20, 24, 56, 60, 72, 80, 164, 168, 180, 188, 216, 224, 236, 240, 488, 492, 504, 512, 540, 548, 560, 564, 648, 656, 668, 672, 704, 708, 720, 728, 1460, 1464, 1476, 1484, 1512, 1520, 1532, 1536, 1620, 1628, 1640, 1644, 1676, 1680, 1692, 1700, 1944, 1952

Offset

1,2

Comments

Apparently a(n)/2 (mod 3) = A010060(n), the Thue-Morse sequence.

Links

Table of n, a(n) for n=1..50.

Formula

a(n) = 4*A083095(n). - Hugo Pfoertner, Jan 12 2025

Mathematica

Select[Range[0, 2000], OddQ[Sum[Mod[Binomial[#, j], 3], {j, 0, #}]] &] (* Paul F. Marrero Romero, Dec 28 2024 *)

Prog

(PARI) isok(n) = sum(k=0, n, binomial(n, k) % 3) % 2; \\ Michel Marcus, Dec 05 2013

Crossrefs

Cf. A010060, A051638, A083093, A083095 (gives a b-file of 16384 terms).

Sequence in context: A205318 A100212 A349168 * A164916 A207190 A110116

Adjacent sequences: A083091 A083092 A083093 * A083095 A083096 A083097

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 22 2003

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 29 2003

Status

approved