

A215121


Strobogrammatic palindromic numbers in their Roman numeral representation.


0




OFFSET

1,2


COMMENTS

Numbers which, written as Roman numerals, are the same upside down and backwards.
Upsidedowninvariant numbers are also called ambigrams. "Upside down" here means rotated by 180° (i.e., central symmetry), NOT "vertically flipped" (symmetry w.r.t. horizontal line).
V, L, C, D, M (5, 50, 100, 500, 1000 in decimal) are not the same upsidedown. Excludes "old style" Roman numeral representation of n (e.g. IIII rather than IV).


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

I, II, III, X, XIX, XX, XXX


CROSSREFS

Cf. A000787, A006968, A078715, A166874.
Sequence in context: A163467 A143045 A156909 * A175569 A275020 A122822
Adjacent sequences: A215118 A215119 A215120 * A215122 A215123 A215124


KEYWORD

nonn,base,fini,full


AUTHOR

Jonathan Vos Post, Aug 03 2012


STATUS

approved



