Talk:Square triangular number

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Square triangular number

Mathematica seems to prefer the term "square triangular number" to "triangular square number". Maybe tri.sq. should be a redirect to sq.tri., but I don't want to move articles unless I'm absolutly sure its the right thing to do. Numerao 22:14, 5 Mar 2004 (UTC)

So do I, but Google makes it pretty even [1] and [2] at about 50 hits each. --Henrygb 14:11, 5 August 2005 (UTC)[reply]

Actually most TSNs seem to come from wikipedia copies, so moved --Henrygb 15:03, 5 August 2005 (UTC)[reply]

square beats triangular: e.g. in the range ]1...1000] there are 43 triangulars but only 30 squares. So the right name must be square triangular number.46.115.1.200 (talk) 21:37, 2 April 2011 (UTC)[reply]

Pell Numbers

I added a new section to Pell numbers. I might suggest redirecting this page to that section. Comments? --Gentlemath (talk) 00:39, 8 March 2009 (UTC)[reply]

This article is in great need of improvement, but it is on a different topic than Pell numbers (although they are obviously closely related) and should I think remain a separate article. —David Eppstein (talk) 01:36, 8 March 2009 (UTC)[reply]

higher dimensions

What's about an enlargement into another dimensions, e.g. "Cube tetrahedral number" (can't find any in the range <1,000,000,000) 46.115.1.200 (talk) 21:50, 2 April 2011 (UTC)[reply]

It is known [3] that the only binomial coefficient

{\binom {n}{k}}

with

k\geq 3

(and

n\geq 2k

) that is also a power of an integer is the case

{\binom {50}{3}}=140^{2}

; apparently this is a result of Erdös. Since tetrahedral numbers are binomial coefficients, this means that no tetrahedral number other than one is a perfect cube, and only 1, 4, and 19600 are perfect squares. —David Eppstein (talk) 22:16, 2 April 2011 (UTC)[reply]