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A180105
Counting integers normally (1, 2, 3, 4, 5...), write them as roman numerals (I, II, III, IV, V...), describe them (one 1, two 1s, three 1s, one 1 one 5, one 5...), and write them out as numbers (11, 21, 31, 1115, 15...).
1
11, 21, 31, 1115, 15, 1511, 1521, 1531, 11110, 110, 11011, 11021, 11031, 1101115, 11015, 1101511, 1101521, 1101531, 11011110, 210, 21011, 21021, 21031, 2101115, 21015, 2101511, 2101521, 2101531, 21011110, 310, 31011, 31021, 31031, 3101115, 31015, 3101511
OFFSET
1,1
LINKS
David Consiglio, Jr., Table of n, a(n) for n = 1..3999
David Consiglio, Jr., Python program
EXAMPLE
For n=9, IX gives one 1 and one 10, so a(9) = 11110.
MATHEMATICA
f[n_] := Block[{w = RomanNumeral@ n}, FromDigits@ Flatten[IntegerDigits /@ {Length@ #, FromRomanNumeral@ First@ #} & /@ Split@ StringPartition[w, 1]]]; Array[f, {36}] (* Michael De Vlieger, Oct 13 2015, Version 10.2 *)
CROSSREFS
Sequence in context: A181178 A178205 A239464 * A288186 A264646 A139113
KEYWORD
nonn,base
AUTHOR
Saiichi Shayan Hashimoto (drako3759(AT)gmail.com), Aug 09 2010
EXTENSIONS
a(9) and a(19) corrected by David Consiglio, Jr., Oct 12 2015
More terms from David Consiglio, Jr., Oct 12 2015
STATUS
approved