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

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