54494domain: NAppears in sequencesNumbers n such that d(n) = phi(n+1) - phi(n), where d(n) denotes the number of divisors of n.at n=9A066171Number of (n+2) X (5+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=17A252381