A078338 Let u(1)=u(2)=u(3)=1 and u(n)=(-1)^n*sign(u(n-1)-u(n-2))*u(n-3), then a(n)=sum(k=1,n,u(k)).

1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 4, 5, 5, 4, 5, 5, 4, 3, 3, 2, 1

Offset

1,2

Links

Table of n, a(n) for n=1..105.

Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 0, 0, 0, 0, 0, -1, 1).

Formula

Periodic with period 18.

Mathematica

LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, -1, 1}, {1, 2, 3, 3, 4, 5, 5, 4, 5, 5}, 105] (* Ray Chandler, Aug 27 2015 *)

Crossrefs

Sequence in context: A240153 A241435 A349320 * A338587 A338580 A278149

Adjacent sequences: A078335 A078336 A078337 * A078339 A078340 A078341

Keyword

nonn

Author

Benoit Cloitre, Nov 21 2002

Status

approved