Python 2, 43 bytes
a=b=0
for x in input():b+=a+x;a=b-a
print b
Takes input as a list. The update is a shorter version of a,b=b+x,a+b+x
, which is like the Fibonacci update a,b=b,a+b
if you ignore x
.
Python 2, 45 bytes
f=lambda n,a=1,b=1:n and n%10*b+f(n/10,b,a+b)
Takes input as decimal numbers.