-10431

Appears in sequences

• Coefficient of X^3 in the characteristic polynomial of the n-th power of the matrix M = {{1,1,1,1,1}, {1,0,0,0,0}, {0,1,0,0,0}, {0,0,1,0,0}, {0,0,0,1,0}}.at n=21A123127
• a(n) = Sum_{k=1..n} (-2)^(n - floor(n/k)).at n=11A345109