A051885(n) = ((n%9)+1)*10^(n\9)-1
a(n) = \
	my (r=0, p=0, d); \
	while (1, \
		d = n%10; \
		if (d<9 && r>0, \
			return ((n+1)*10^p + A051885(r-1)) \
		); \
		n = n\10; \
		p = p+1; \
		r = r+d \
	)