-2431

Appears in sequences

• Numerators in expansion of sqrt(1+x). Absolute values give numerators in expansion of sqrt(1-x).at n=10A002596
• Expansion of Product_{k>=1} (1 - x^k)^11.at n=17A010819
• Numerator of Maclaurin expansion of (t*sqrt(t^2+1) + arcsinh(t))/2, the arc length of Archimedes' spiral.at n=10A091154
• First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 401", based on the 5-celled von Neumann neighborhood.at n=25A271806
• a(n) is the A-sequence for the Riordan matrix R = (1/(1- x^2 - x^3), x/(1 - x^2 - x^3)) from A104578.at n=15A319202
• G.f.: A(x,y) = Sum_{n=-oo..+oo} (x*y)^(n*(n+1)/2) * C(x)^(2*n-1), where C(x) = 1 + x*C(x)^2 is the g.f. of the Catalan numbers (A000108).at n=45A355346
• Triangle read by rows: T(n, k) = (-1)^(n + 1)*L(n) * M(n, k) where M is the inverse of the matrix generated by the triangle A368846 and L(n) is the lcm of the denominators of the terms in the n-th row of M.at n=25A369134
• Partial alternating sums of the sigma_2 function: a(n) = Sum_{k=1..n} (-1)^(k+1) * sigma_2(k).at n=31A379921