Suppose a2,a3,a4,a5,a6,a7 are integers such that
57=a22!+a33!+a44+a55!+a66!+a77!
where 0≤a<j for j=2,4,5,6,7. The sum a2+a3+a4+a5+a6+a7 is
57=a22!+a33!+a44!+a55!+a66!+a77!⇒57=12(a2+13(a3+14(a4+......(a77))))107=a2+13(a3+14(a4+......(a77)))1+37=a2+13(a3+14(a4+......(a77)))
So, as expression is less than 1
a2=137=13(a3+14(a4+......15(a5+.....a77)))1+27=a3+14(a4+......15(a5+16(a6+a77)))a3=1
Similarly
a4=1a7=2a5=0a6=4
So, Sum a7−1+1+1+4+2=9