All numbers of the forms 5a*7b*8c, 2*5a*7b*8c, 3*5a*7b*8c, 4*5a*7b*8c or 2*5a*6*7b*8c must be checked. d(n,b) must not contain a zero or at most 1 by 3 divedably digit (3,6). Maximale a+b+c without holding the 0er-criteria was 152. All numbers with a+b+c<=1000 were checked. Only the last 60 digits were needed..
