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# User talk:Jonathan Vos Post

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## A003313 - length of shortest addition chain

Dear Jonathan,

In the page about A003313, you wrote that "a(n) =< (4/3)floor(log_2 n) + 2".

What is a reference for this upper bound?

Thanks! --Erel Segal-Halevi 14:32, 10 September 2015 (UTC)

## A001131 - Number of red-black rooted trees with n-1 internal nodes.

Dear Jonathan,

In the page about A001131, you wrote under FORMULA "[(2m)C(n-2m) * a(m)}" 2 questions: 1) Is the pairing [} intended and what does it mean ? 2) What is C and what does it mean ?

Best regards and thanx! --Herbert Eberle 15:28, 2 October 2015 (UTC)

[I answered this question and improved the formula in A001131. This question has been resolved. - N. J. A. Sloane 01:20, 4 October 2015 (UTC)]