A. Werner
The sums of progressions: 1,2,3,4,5..., -1,-2,-3,-4,-5... can be found using the formula: Sn= (a₁n²+n)/2. The sums of progressions: 1,3,6,10,15..., -1,-3,-6,-10,-15... can be found using the formula:Sn= ((n+a₁)³-(n+a₁))/6. The sums of progressions: 1,4,9,16,25..., -1,-4,-9,-16,-25... can...
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Progressive sums:-1,-2,-3,-4,-5... 1,2,3,4,5... We express the formulas: Sn=...