1,2

All pairs (i,j) having i > j occur except those of the form (i,i-1) for i>=3. (Those are included at A097285.)

Table of n, a(n) for n=1..98.

Terms are lexically ordered in pairs by sum:

1 2 (sum = 3)

1 3 (sum = 4)

1 4 2 3 (two pairs having sum = 5), etc.

Cf. A097284, A097285.

Sequence in context: A079617 A079616 A292587 * A296119 A300836 A118314

Adjacent sequences: A097280 A097281 A097282 * A097284 A097285 A097286

nonn

Clark Kimberling, Aug 05 2004

approved