-781

Appears in sequences

• Expansion of log(1+tan(x))/cos(x).at n=6A009372
• Triangle c(n,k) of the numerators of coefficients [x^k] P(n,x) of the polynomials P(n,x) of A129891.at n=60A140749
• First differences of A060819(n-4)*A060819(n).at n=30A185688
• G.f.: Sum_{n>=0} (x^n - 1)^n * x^n / (1-x)^(n+1).at n=22A243919
• Alternating sum of 9-gonal (or nonagonal) numbers.at n=21A266086
• Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1 - j^k*x^j).at n=49A292166
• a(n) = 2^(3n+1)*cos(nB), where B is the angle opposite side CA in a triangle ABC having sidelengths |BC|=2, |CA| = 3, |AB| = 4; ABC is the smallest integer-sided scalene triangle.at n=3A375881