A071622 a(n) = (-1)*Sum_{k=1..n} (-1)^floor((4/3)^k).

1, 2, 1, 2, 1, 2, 3, 4, 5, 6, 7, 8, 7, 6, 5, 6, 7, 8, 7, 8, 7, 6, 7, 6, 5, 6, 5, 6, 7, 8, 7, 6, 7, 8, 7, 6, 5, 6, 7, 8, 9, 10, 11, 12, 11, 10, 9, 10, 11, 10, 9, 8, 7, 8, 7, 8, 7, 8, 9, 10, 9, 8, 9, 8, 9, 8, 7, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 14, 15, 14, 13, 12, 13, 12, 13, 12, 11, 10, 9, 10, 9

Offset: 1

Author

Benoit Cloitre, Jun 22 2002

Keywords

• easy
• nonn

Comments

Conjecture: for n>2300, a(n) > log(n)^2.

Crossrefs

Cf. A071532.

Programs

Mathematica

Table[(-1)Sum[(-1)^Floor[(4/3)^k],{k,n}],{n,100}] (* Harvey P. Dale, Jul 27 2025 *)

PARI

for(n=1,100,print1(-sum(i=1,n,sign((-1)^floor((4/3)^i))),","))