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A072175
a(1)=1, a(2)=2, a(n) = a(n-1) + 1 - 2*sign(a(n-2)) for n>2.
0
1, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3, 2, 1, 0, -1, 0, 3, 4, 3
OFFSET
0,2
COMMENTS
The sequence has period 8 except for the first term.
REFERENCES
Marius-F. Danca, Contributions to the Theory of Discontinuous Dynamical System, Thesis 2002, University Babes-Bolyai, Cluj, Romania, page 5
FORMULA
a(n) = a(n-1)-a(n-2)+a(n-3)-a(n-4)+a(n-5)-a(n-6)+a(n-7). - Wesley Ivan Hurt, May 26 2024
EXAMPLE
a(3) = 2+1-2*sign(1) = 1.
a(4) = 1+1-2*sign(2) = 0.
MATHEMATICA
a[1]=1; a[2]=2; a[n_] := a[n]=a[n-1]+1-2Sign[a[n-2]]
CROSSREFS
Sequence in context: A123022 A072943 A372596 * A280712 A363926 A306607
KEYWORD
sign,easy,less
AUTHOR
Roger L. Bagula, Jun 29 2002
EXTENSIONS
Edited by Dean Hickerson, Jul 31 2002
STATUS
approved