OFFSET
1,4
COMMENTS
Sequence created using classic Roman numerals, i.e., 99 = XCIX, not the questionable IC.
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 1..3999
Eric Weisstein's World of Mathematics, Roman Numerals
Wikipedia, Roman numerals
FORMULA
EXAMPLE
a(97) = 4 as you need I, V, X and C to express XCVII.
MAPLE
with(StringTools): A057226 := proc(n) local r: r:=convert(n, roman): return `if`(Search("I", r)>0, 1, 0) + `if`(Search("V", r)>0, 1, 0) + `if`(Search("X", r)>0, 1, 0) + `if`(Search("L", r)>0, 1, 0) + `if`(Search("C", r)>0, 1, 0) + `if`(Search("D", r)>0, 1, 0) + `if`(Search("M", r)>0, 1, 0): end: seq(A057226(n), n=1..105); # Nathaniel Johnston, May 18 2011
MATHEMATICA
Table[Length[Union[Characters[IntegerString[n, "Roman"]]]], {n, 110}] (* Harvey P. Dale, Mar 18 2013 *)
PROG
(Haskell)
a057226 = a043537 . a061493 -- Reinhard Zumkeller, Apr 14 2013
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Helge T. Blohmer (crusher(AT)k-town.de), Sep 19 2000
STATUS
approved