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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 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 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 30 20:17 EST 2021. Contains 349425 sequences. (Running on oeis4.)