A117136 - OEIS

%I #5 Mar 31 2012 13:21:30

%S 1,1,1,2,4,1,1,3,6,2,7,1,1,4,8,3,9,2,10,1,1,5,10,4,11,3,12,2,13,1,1,6,

%T 12,5,13,4,14,3,15,2,16,1,1,7,14,6,15,5,16,4,17,3,18,2,19,1

%N Triangle read by rows: row n always begins with 1. Later terms in row n are obtained by successively subtracting or adding the numbers n, n+1, n+2, until reaching 1 again. The rule is that you subtract if the result is positive, otherwise you add.

%C Row n has length 2n+2.

%F T(n,0) = 1. For 0<k<=n+1, T(n,2k-1) = n+2-k, T(n,2k) = 2n+1+k. - _Franklin T. Adams-Watters_, Apr 26 2006

%e Triangle begins:

%e Row 0: 1 1

%e Row 1: 1 2 4 1

%e Row 2: 1 3 6 2 7 1

%e Row 3: 1 4 8 3 9 2 10 1

%e Row 4: 1 5 10 4 11 3 12 2 13 1

%e ...

%K nonn,tabf

%O 0,4

%A _N. J. A. Sloane_, Apr 21 2006