0,9

David Applegate and N. J. A. Sloane, The Gift Exchange Problem (arXiv:0907.0513, 2009)

Triangle begins:

1

0 1

0 1 1

0 1 3 1

0 1 7 6 1

0 1 15 25 10 1

0 0 31 90 65 15 1

0 0 56 301 350 140 21 1

0 0 91 938 1701 1050 266 28 1

Sequence in context: A055807 A054024 A144644 this_sequence A151511 A048993 A112413

Adjacent sequences: A151506 A151507 A151508 this_sequence A151510 A151511 A151512

nonn,tabl,easy,more

N. J. A. Sloane (njas(AT)research.att.com), May 14 2009