A125849 a(n) = Sum_{m=1..n-1} floor(m(n-2)/2)^2.
0, 0, 0, 1, 14, 62, 220, 547, 1260, 2444, 4560, 7685, 12650, 19466, 29484, 42567, 60760, 83672, 114240, 151689, 200070, 258070, 331100, 417131, 523204, 646372, 795600, 966797, 1171170, 1403234, 1676780, 1984655, 2343600, 2744496, 3207424
Offset: 0
Keywords
Programs
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Maple
for n from 0 to 15 do add( floor(m*(n-2)/2)^2,m=1..n-1) ; print(n,%) ; od: # R. J. Mathar
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Mathematica
f[n_] := Sum[ Floor[m (n - 2)/2]^2, {m, n - 1}]; Table[ f@n, {n, 0, 35}] (* Robert G. Wilson v, Aug 03 2008 *)
Formula
G.f.: (x^3*(x^6+18*x^5+35*x^4+62*x^3+31*x^2+12*x+1))/((x+1)^4*(x-1)^6). - Maksym Voznyy (voznyy(AT)mail.ru), Jul 28 2009
Extensions
More terms from Robert G. Wilson v, Aug 03 2008