Sequences and Summation Formulas

∑k

[n(n+1)]/2

∑c

cn

geometric sequence sum

[a(1-rⁿ)]/(1-r)

arithmetic sequences sum

[n(a1+an)]/2

∑k²

[n(n+1)(2n+1)]/6

∑k³

[n²(n+1)²]/4

geometric sequence

a(r)ⁿ⁻¹

arithmetic sequence

a+(n-1)d

∑ca

c∑a

∑(a+b)

∑a + ∑b