Sprendimas:
$$S_{1} = 4\cdot 1^{2}+4\cdot 1 = 4+4 = 8$$
Atsakymas: 8
Sprendimas:
$$S_{2n} = 4\cdot (2\cdot n)^{2}+4\cdot (2\cdot n)$$
$$S_{n} = 4\cdot n^{2}+4\cdot n$$
$$4\cdot (2\cdot n)^{2}+4\cdot (2\cdot n)$$ = $$\frac{11}{3}\cdot (4\cdot n^{2}+4\cdot n)$$
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