-1570

Appears in sequences

• G.f. A(x) satisfies: [x^n] A_{n}(x) = [x^n] A_{n+1}(x) for n>2 where A_{n+1}(x) = A_{n}(A(x)) denotes iteration with A_0(x)=x.at n=4A177776
• G.f.: Im((2*i; x)_oo), where (a; q)_oo is the q-Pochhammer symbol, i = sqrt(-1).at n=31A292140
• Partial alternating sums of the sigma_2 function: a(n) = Sum_{k=1..n} (-1)^(k+1) * sigma_2(k).at n=27A379921