-2090

Appears in sequences

• a(n) = -n^2 - n + 72.at n=46A110678
• a(n) = (-1)^n*n*(n+1)*(2*n-5)/6.at n=18A167386
• a(n) = 2*sigma(n^2) - sigma(n)^2.at n=47A195735
• Expansion of (1+4*x+x^2) / ((1-x)^3*(1+x)^4).at n=36A229834
• Difference between sums of quadratic residues and non-residues modulo n that are coprime to n.at n=94A255643
• G.f.: 1/(1 + (x + x)/(1 + (x + x^2)/(1 + (x + x^3)/(1 + (x + x^4)/(1 ...))))), a continued fraction.at n=7A352076