589815domain: NAppears in sequencesNumbers n such that phi(n)+phi(n+1)=n+1.at n=40A067798Triangle read by rows: (1/5) * (A007318^4 - A007318^(-1)) as infinite lower triangular matrices.at n=47A131050Numbers all of whose divisors, excluding the divisor 1, are evil numbers (A001969) with a record number of divisors.at n=9A338611