-645
domain: Z
Appears in sequences
- Coefficients of period polynomials.at n=12A006309
- cos(cos(x)*arctan(x))=1-1/2!*x^2+21/4!*x^4-645/6!*x^6+34153/8!*x^8...at n=3A012501
- Expansion of (1-x)/(1+2*x^2-x^3).at n=16A078035
- Consider the triangle in which the n-th row starts with n, contains n terms and the difference of successive terms is 1,2,3,... up to n-1. Sequence gives row sums.at n=17A081498
- a(n) = 2*a(n-1) - a(n-2) - a(n-4).at n=18A131041
- G.f.: 1/(1 + x + 5*x^2 - x^3 + x^4).at n=11A199805
- a(n) = Pell(n) * Sum_{d|n} (-1)^(n/d) / Pell(d), where Pell(n) = A000129(n).at n=7A204059
- a(n) = nearest integer to n^2 * sin(sqrt(n)).at n=27A274088
- Take alternate terms of A274088 and A274090.at n=54A274091
- Expansion of f(x)^3 * f(-x^2) * chi(x^3)^3 in powers of x where chi(), f() are Ramanujan theta functions.at n=33A280384
- a(n) = A325978(A228058(n)).at n=47A389218