1666224

Appears in sequences

• (-1)sigma perfect numbers: (-1)sigma(a) = m*a for some integer m, where if a = Product p(i)^r(i) then (-1)sigma(a) = Product_{i} (-1 + Sum_{s=1..r(i)} p(i)^s).at n=6A034094
• a(n) = n-th quintic factorial number divided by 4.at n=5A034301
• a(n) = (n+1)*a(n-5), with a(0)=a(1)=a(2)=a(3)=a(4)=1.at n=28A081408