A072175 a(1)=1, a(2)=2, a(n) = a(n-1) + 1 - 2*sign(a(n-2)) for n>2.

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

Links

Table of n, a(n) for n=0..104.

Index entries for linear recurrences with constant coefficients, signature (1,-1,1,-1,1,-1,1).

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

Adjacent sequences: A072172 A072173 A072174 * A072176 A072177 A072178

Keyword

sign,easy,less

Author

Roger L. Bagula, Jun 29 2002

Extensions

Edited by Dean Hickerson, Jul 31 2002

Status

approved