21704

Appears in sequences

• Cluster series for bond percolation problem on honeycomb.at n=16A003199
• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 73.at n=38A031571
• Real part of absolute Gaussian perfect numbers, in order of increasing magnitude.at n=30A102531
• Symmetrical triangle sequence from polynomials: q(x,n)=-((-1)^n*(Sum[(k + 1)^n*x^k/k^2, {k, 1, Infinity}] - PolyLog[2, x])*(x - 1)^(n - 1) + (-1)^n*n *(-1 + x)^(n - 1) Log[1 - x])/x; p(x,n)=q(x,n)+x^n*q(1/x,n).at n=38A154991
• Symmetrical triangle sequence from polynomials: q(x,n)=-((-1)^n*(Sum[(k + 1)^n*x^k/k^2, {k, 1, Infinity}] - PolyLog[2, x])*(x - 1)^(n - 1) + (-1)^n*n *(-1 + x)^(n - 1) Log[1 - x])/x; p(x,n)=q(x,n)+x^n*q(1/x,n).at n=42A154991
• Expansion of 1 / ((1-x)^2*(1-x^2)*(1-x^3)*...*(1-x^9)).at n=31A288344
• Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-1)^2, where a(0) = 1, a(1) = 4, b(0) = 2, b(1) = 3, and (a(n)) and (b(n)) are increasing complementary sequences.at n=14A296253
• Number of n X 6 0..1 arrays with every element unequal to 0, 1, 3 or 6 king-move adjacent elements, with upper left element zero.at n=10A304131