A097425 Write down ten thousanD; D is the only Roman number visible, = 500, so a(1) = 500; fIVe unDreD = 15500500, which is the second term; fIVeteen MILLIon fIVe unDreD thousanD fIVe unDreD = 1 5 1000 1 50 50 1 1 5 500 500 500 1 5 500 500; etc.

500, 15500500, 1510001505011550050050015500500