A097425 a(1) = 500, then a(n) is the concatenation of the roman numerals (I, V, X, L, C, D, M) visible in a(n-1) written in English.

500, 15500500, 1510001505011550050050015500500

Offset: 1

Author

Pierre CAMI, Aug 21 2004

Keywords

• nonn
• word
• less

Examples

			a(1) = 500, which is fIVe hunDreD, so a(2) = concat(1, 5, 500, 500) = 15500500, which is fIVeteen MILLIon fIVe hunDreD thousanD fIVe hunDreD, so a(3) = concat(1, 5, 1000, 1, 50, 50, 1, 1, 5, 500, 500, 500, 1, 5, 500, 500), etc.
		

Crossrefs

Cf. A002904, A092302.