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Square numbers which equal a triangular number times an odd number between 1 and 15.
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%I #10 Jul 02 2022 16:08:03

%S 1,9,36,196,225,324,900,1225,4225,11025,41616,53361,88209,108900,

%T 176400,324900,374544,1413721,8643600,12723489,43956900,48024900,

%U 52490025,158407396,432224100,468506025,846984609,1631432881

%N Square numbers which equal a triangular number times an odd number between 1 and 15.

%H Valladolid problem set archive, <a href="http://web.archive.org/web/20071118024255/http://acm.uva.es/p/v102/10241.html">Semi-triangular and also square</a>

%t Select[Union[Flatten[# Range[1,15,2]&/@Accumulate[Range[60000]]]], IntegerQ[Sqrt[#]]&] (* _Harvey P. Dale_, Nov 02 2011 *)

%Y Cf. A000217, A000290.

%K nonn

%O 1,2

%A Rahman Md. Miaznur (m_rahmanjewel(AT)yahoo.com), Aug 26 2004

%E Edited by _Don Reble_, Mar 17 2007