A089045 - OEIS

A089045

a(n) = a(n-1) + (-1)^floor(n/2)*a(floor(n/2)) with a(1) = 1.

1, 0, -1, -1, -1, 0, 1, 0, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, 0, 1, 0, -1, -1, -1, 0, 1, 0, -1, 0, 1, 1, 1, 0, -1, 0, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 0, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, 0, 1, 0, -1, -1, -1, 0, 1, 1, 1, 0, -1, -1, -1, 0, 1, 0, -1, 0, 1, 1, 1, 0, -1, 0, 1, 0, -1, -1, -1, 0, 1, 0, -1, 0, 1, 1, 1, 0

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

OFFSET

1,1

LINKS

Jinyuan Wang, Table of n, a(n) for n = 1..1000

FORMULA

abs(a(n)) = A035263(n).

PROG

(PARI) lista(nn) = {my(v=vector(nn)); v[1]=1; for(n=2, nn, v[n] = v[n-1] + (-1)^floor(n/2)*v[floor(n/2)]); v; } \\ Jinyuan Wang, Feb 27 2020

CROSSREFS

Cf. A001511, A035263.

Sequence in context: A141260 A029883 A035263 * A259599 A070749 A285341

Adjacent sequences: A089042 A089043 A089044 * A089046 A089047 A089048

KEYWORD

sign

AUTHOR

Benoit Cloitre, Dec 02 2003

STATUS

approved