A317540 - OEIS

A317540

a(-1) = -1, a(0) = 1, a(n) = A317539(n) - 3*(n-1) for n > 0.

-1, 1, 2, 0, 2, 1, -1, 0, -1, 1, -1, 0, 2, 1, 2, 0, -1, 1, -1, 0, 2, 1, -1, 0, -1, 1, 2, 0, 2, 1, 2, 0, -1, 1, -1, 0, 2, 1, -1, 0, -1, 1, -1, 0, 2, 1, 2, 0, -1, 1, 2, 0, 2, 1, -1, 0, -1, 1, 2, 0, 2, 1, 2, 0, -1, 1, -1, 0, 2, 1, -1, 0, -1, 1, -1

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OFFSET

-1,3

LINKS

Table of n, a(n) for n=-1..73.

FORMULA

a(-1) = -1, a(1) = 2, a(4n) = 1, a(4n+2) = 0, a(8n+3) = 2, a(8n+7) = -1, a(8n+1) = a(4n+1), a(1) = 2, a(8n+5) = a(4n-1), for n >= 0.

PROG

(Python)

a = [-1, 1, 2]

print(-1, -1)

print(0, 1)

print(1, 2)

n = 2

while n < 128:

if n%4 == 0:

a = a+[1]

elif n%4 == 2:

a = a+[0]

elif n%8 == 1:

a = a+[a[4*(n//8)+2]]

elif n%8 == 3:

a = a+[2]

elif n%8 == 5:

a = a+[a[4*(n//8)]]

else: # n%8 == 7

a = a+[-1]

print(n, a[n+1])

n = n+1

CROSSREFS

Cf. A317539.

Sequence in context: A060950 A039976 A287267 * A133701 A230417 A287263

Adjacent sequences: A317537 A317538 A317539 * A317541 A317542 A317543

KEYWORD

sign

AUTHOR

A.H.M. Smeets, Jul 30 2018

EXTENSIONS

Offset and NAME corrected by R. J. Mathar, Jun 19 2021

STATUS

approved