1,2

The term a(5) = 99999999999999999999 is a fake, inserted to prevent this sequence being incorrectly returned by Superseeker. Of course it will be replaced by the correct value, once that is determined.

The present state of knowledge, quoting from Ge & Lam and the link below, is that a TWh(n) exists iff n == 0 or 1 (mod 4), except for n = 5, 9, 12 and possibly excepting n in {17, 57, 65, 69, 77, 85, 93, 117, 129, 153}.

After 16, the sequence continues 17?, 20, 21, 24, 25, 28, 29, 32, 33, 36, 37, 40, 41, 44, 45, 48, 49, 52, 53, 56, 57?, ...

G. Ge and C. W. H. Lam, Some new triplewhist tournaments TWh(v), J. Combinat. Theory, A101 (2003), 153-159.

Harri Haanpaa and Petteri Kaski, The near resolvable 2-(13,4,3) designs and. thirteen-player whist tournaments, [shows that no TWh(13) exists]

Sequence in context: A038110 A130436 A090804 this_sequence A031462 A045066 A151911

Adjacent sequences: A074022 A074023 A074024 this_sequence A074026 A074027 A074028

nonn,more,nice

N. J. A. Sloane (njas(AT)research.att.com), Oct 16 2003

Of course this entry is much too short. But I have included it in the hope that this will encourage someone to settle the question of whether a(5) is 17 or 20 - i.e. does a TWh(17) exist?

Link supplied by Jon Schoenfield, Aug 01 2006