A237623 Two-Special Pairs in a Free Group

0, 0, 0, 0, 0, 1, 2, 6, 14, 30, 62, 129, 252, 499, 984, 1884, 3624, 7025, 13358, 25694, 49316

Offset

1,7

Comments

a(n) is the number of pairs of positive words of length n in a free group of rank 2 such that the words are not conjugate and they have the same SL(2,C) trace functions. This sequence was discovered by Julian Caballero, Ruben Espinoza, Carlos Salinas under the supervision of Sean D Lawton.

Links

Table of n, a(n) for n=1..21.

Crossrefs

Cf. A059076.

Sequence in context: A296965 A000918 A059076 * A232059 A343889 A263711

Adjacent sequences: A237620 A237621 A237622 * A237624 A237625 A237626

Keyword

nonn,more

Author

Sean D Lawton, Feb 10 2014

Status

approved