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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. 1
4, 0, 8, 0, 4, 12, 0, 0, 18, 14, 0, 0, 10, 44, 10, 0, 0, 0, 50, 74, 4 (list; table; graph; refs; listen; history; text; internal format)
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: A261278 A222609 A247848 * A070802 A114401 A304440

Adjacent sequences:  A076258 A076259 A076260 * A076262 A076263 A076264

KEYWORD

more,nonn,tabl

AUTHOR

Colin Mallows, Oct 03 2002

STATUS

approved

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Last modified November 15 22:20 EST 2018. Contains 317252 sequences. (Running on oeis4.)