mybe this time

a = [[2,3,4],
    [5,6,7],
    [8,9,10],
    [11,12,13],
    [14,15,16]]










def average(a):
    w=len(a[0])
    h=len(a)
    c=[]
    for y in range(0,h):
        l=[]
        m=[]
        r=[]
        for i in range(y-1,y+2):
                if i>=0 and i<h:
                    m.append(a[i][0])
                    r.append(a[i][1])
        R=[]
        for x in range(1,w+1):
            R.append((int)(sum(l+m+r)/(len(l+m+r))))
            l=m
            m=r
            r=[]
            for i in range(y-1,y+2):
                if i>=0 and i<h and (x+1)<w:
                    r.append(a[i][x+1])
        c.append(R)
    return c








avr = average(a)


print ("a: ")
for R in a:
    print (R)


print ("\n\n\naverage: ")
for R in avr:
    print (R)