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 A075405 a(n)^2 is the square obtained in A075404 (or 0 if no such square exists). 4

%I #13 Mar 30 2012 17:35:31

%S 70,0,5,0,0,0,92,0,106,0,2001863,0,652,0,679,0,138,77,0,29,724,413,0,

%T 0,182,0,253,385,0,1612,0,8687,0,0,0,0,0,143,0,0,0,0,0,274,0,0,0,0,0,

%U 1281,0,1012,0,0,121268,0,0,56855,0,440,0,0,0,3069,2725,0,655,0,0,0,0,0,1525,4035066,0,430,0,0,0,0,0,0,2619,0,0,0,795,0,0,0,3465,0,0,0,0,0,0,0,0,0

%N a(n)^2 is the square obtained in A075404 (or 0 if no such square exists).

%D See A180244.

%e a(1) = 70 because 1^2+...+24^2 = a(1)^2 = 70^2.

%t s[n_, k_]:=Module[{m=n+k-1}, (m(m+1)(2m+1)-n(n-1)(2n-1))/6]; mx=40000; Table[k=2; While[k<mx && !IntegerQ[Sqrt[s[n, k]]], k++]; If[k==mx, 0, Sqrt[s[n, k]]], {n, 100}]

%Y Cf. A000330, A075404, A075406.

%K nonn

%O 1,1

%A _Zak Seidov_, Sep 13 2002

%E Corrected and extended by _Lior Manor_ Sep 19 2002

%E Corrected and edited by _T. D. Noe_, Jan 21 2011

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Last modified September 12 22:20 EDT 2024. Contains 375855 sequences. (Running on oeis4.)