a(0)=0 and for n>0, a(n) is the smallest positive integer that cannot be derived by the adding or subtracting at most three terms with values in {a(0),...,a(n-1)} allowing repeats.

A096077

a(0)=0 and for n>0, a(n) is the smallest positive integer that cannot be derived by the adding or subtracting at most three terms with values in {a(0),...,a(n-1)} allowing repeats.