A117136 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.

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

Offset: 0

Author

N. J. A. Sloane, Apr 21 2006

Keywords

• nonn
• tabf

Comments

Row n has length 2n+2.

Examples

			Triangle begins:
Row 0: 1 1
Row 1: 1 2 4 1
Row 2: 1 3 6 2 7 1
Row 3: 1 4 8 3 9 2 10 1
Row 4: 1 5 10 4 11 3 12 2 13 1
...
		

Formula

T(n,0) = 1. For 0Franklin T. Adams-Watters, Apr 26 2006