A124759 Sum of products of consecutive terms for compositions in standard order.

0, 0, 0, 1, 0, 2, 2, 2, 0, 3, 4, 3, 3, 4, 3, 3, 0, 4, 6, 4, 6, 6, 4, 4, 4, 6, 6, 5, 4, 5, 4, 4, 0, 5, 8, 5, 9, 8, 5, 5, 8, 9, 8, 7, 5, 6, 5, 5, 5, 8, 9, 7, 8, 8, 6, 6, 5, 7, 7, 6, 5, 6, 5, 5, 0, 6, 10, 6, 12, 10, 6, 6, 12, 12, 10, 9, 6, 7, 6, 6, 10, 12, 12, 10, 10, 10, 8, 8, 6, 8, 8, 7, 6, 7, 6, 6, 6, 10

Offset: 0

Author

Franklin T. Adams-Watters, Nov 06 2006

Keywords

• easy
• nonn
• tabf

Comments

The standard order of compositions is given by A066099.

Examples

			Composition number 11 is 2,1,1; 2*1+1*1 = 3, so a(11) = 3.
The table starts:
0
0
0 1
0 2 2 2
		

Links

• Alois P. Heinz, Rows n = 0..14, flattened

Crossrefs

Cf. A066099, A070939, A011782 (row lengths), A045618 (row sums).

Formula

For a composition b(1),...,b(k), a(n) = Sum_{i=1}^{k-1} b(i) b(i+1).