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A076262 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 three generators that require exactly k multiplications for their formation. 1
9, 0, 27, 0, 9, 72, 0, 0, 69, 174 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..11.

EXAMPLE

T(4,2)= 9 because each of aaaa,bbbb,cccc,abab,acac,baba,bcbc,caca,cbcb can be formed in just two multiplications: e.g. ab=a*b, abab=ab*ab.

CROSSREFS

Cf. A076261.

Sequence in context: A057405 A167354 A005066 * A167301 A177741 A182213

Adjacent sequences:  A076259 A076260 A076261 * A076263 A076264 A076265

KEYWORD

more,nonn,tabl

AUTHOR

Colin Mallows, Oct 03 2002

STATUS

approved

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Last modified May 6 18:38 EDT 2021. Contains 343586 sequences. (Running on oeis4.)