51811

Appears in sequences

• Expansion of g.f.: 1/(1 + 2*x + 9*x^2).at n=10A025170
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 87 ones.at n=1A031855
• Expansion of 1/(1 - 2*x + 9*x^2).at n=10A127357
• Transform of the finite sequence (1, 0, -1, 0, 1) by the T_{1,0} transformation (see link).at n=13A159337
• G.f.: A(x) = exp( Sum_{n>=1} A179307(n)*x^n/n ), where A179307(n) = Sum_{d|n} C(n,d)*sigma(d)*sigma(n/d).at n=12A179306