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A160677 Numbers k such that k, 2k and 3k use the same number of characters when expressed in Roman numerals. 4
2, 7, 20, 22, 36, 70, 72, 97, 153, 200, 202, 207, 220, 222, 236, 315, 351, 360, 362, 379, 448, 653, 700, 702, 707, 720, 722, 736, 871, 970, 972, 997, 1035, 1087, 1177, 1235, 1267, 1350, 1352, 1357, 1386, 1537, 1677, 1735, 1767, 1818, 1836, 1870, 1872, 1897 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

2 = II, 4 = IV, 6 = VI;

7 = VII, 14 = XIV, 21 = XXI;

20 = XX, 40 = XL, 60 = LX.

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..57 (complete up to 3999)

MAPLE

for n from 1 to 3999 do if(length(convert(n, roman)) = length(convert(2*n, roman)) and length(convert(n, roman)) = length(convert(3*n, roman)))then printf("%d, ", n): fi: od: # Nathaniel Johnston, May 18 2011

CROSSREFS

Cf. A006968.

Sequence in context: A170869 A162355 A045858 * A035402 A182655 A136907

Adjacent sequences:  A160674 A160675 A160676 * A160678 A160679 A160680

KEYWORD

nonn,easy

AUTHOR

Claudio Meller, May 23 2009, May 24 2009

EXTENSIONS

Extended by Nathaniel Johnston, May 18 2011

STATUS

approved

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Last modified October 20 00:34 EDT 2021. Contains 348097 sequences. (Running on oeis4.)