90774

Appears in sequences

• Composite numbers k+1 such that k*phi(k+1) is a perfect square.at n=40A069068
• Number of nonnegative integer arrays of length n+2 with new values 0 upwards introduced in order, no three adjacent elements equal, and containing the value 2.at n=7A211829
• T(n,k)=Number of nonnegative integer arrays of length n+k+1 with new values 0 upwards introduced in order, no three adjacent elements equal, and containing the value k+1.at n=35A211836
• a(n) = Sum_{k=1..n} phi(k)*phi(k+1)*phi(k+2), where phi(k) = A000010(k) is Euler's totient function.at n=35A335131