A076261 Triangle T(n,k) (n >= 2, 1 <= k <= n-1) read by rows, where T(n,k) is the number of words of length n in the free group on two generators that require exactly k multiplications for their formation.

4, 0, 8, 0, 4, 12, 0, 0, 18, 14, 0, 0, 10, 44, 10, 0, 0, 0, 50, 74, 4

Offset

2,1

Links

Table of n, a(n) for n=2..22.

Example

T(4,2)=4 because we can generate each of aaaa,abab,baba,bbbb with just two multiplications: e.g. ab=a*b, abab=ab*ab.

Crossrefs

Cf. A076262.

Sequence in context: A340424 A222609 A247848 * A070802 A114401 A378617

Adjacent sequences: A076258 A076259 A076260 * A076262 A076263 A076264

Keyword

more,nonn,tabl

Author

Colin Mallows, Oct 03 2002

Status

approved