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URL: https://oeis.org/A359368

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A359368
Sequence begins 1, 1, 1; for even n > 3, a(n) = a(n/2 - 1) + a(n/2 + 1); for odd n > 3, a(n) = -a((n-1)/2).
1
1, 1, 1, 2, -1, 3, -1, 0, -2, 5, 1, -2, -3, 3, 1, -3, 0, 5, 2, -1, -5, 3, -1, -2, 2, 1, 3, -2, -3, 0, -1, 1, 3, 2, 0, 2, -5, 4, -2, -3, 1, 2, 5, -6, -3, 1, 1, 1, 2, -1, -2, 5, -1, -1, -3, 0, 2, -2, 3, -4, 0, 1, 1, 2, -1, 3, -3, 3, -2, 4, 0, -5, -2, 6, 5, -7, -4, 1, 2, -1
OFFSET
1,4
LINKS
EXAMPLE
The recurrence for the terms begins:
a(4) = a(1) + a(3) = 2
a(5) = -a(2) = -1
a(6) = a(2) + a(4) = 3
a(7) = -a(3) = -1
a(8) = a(3) + a(5) = 0
a(9) = -a(4) = -2
MATHEMATICA
a[1]=a[2]=a[3]=1; a[n_]:=If[EvenQ[n], a[n/2-1]+a[n/2+1], -a[(n-1)/2]]; Array[a, 80] (* Stefano Spezia, Dec 29 2022 *)
PROG
(Python)
def Seq(n): # generates n terms
seq = [1, 1, 1]
k = 0
while len(seq) < n:
seq += [seq[k] + seq[k+2]]
seq += [-1*seq[k+1]]
k += 1
return seq
(PARI) \\ See links.
CROSSREFS
Sequence in context: A160550 A172038 A331363 * A353490 A377051 A226131
KEYWORD
sign,easy
AUTHOR
Eden Lippmann, Dec 28 2022
STATUS
approved