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Sum of the first n^2 squares.
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%I #10 Apr 30 2016 18:56:03

%S 0,14,204,1240,4900,14910,38024,85344,173880,328350,583220,984984,

%T 1594684,2490670,3771600,5559680,8004144,11284974,15616860,21253400,

%U 28491540,37676254,49205464,63535200,81185000,102743550,128874564

%N Sum of the first n^2 squares.

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).

%F a(n) = n^2*(n^2-1)*(2*n^2-1)/6. G.f.: 2*x^2*(1+x)*(7*x^2+46*x+7)/(1-x)^7. [From _R. J. Mathar_, Jun 28 2010]

%o (PARI) for(j=1,50,print1(sum(i=0,j^2-1,i^2),",")) (Klasen)

%K easy,nonn

%O 1,2

%A _Giovanni Teofilatto_, Aug 13 2005