A160677 Numbers k such that k, 2k and 3k use the same number of characters when expressed in Roman numerals.

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

Offset: 1

Author

Claudio Meller, May 23 2009, May 24 2009

Keywords

• nonn
• easy

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)

Crossrefs

Cf. A006968.

Programs

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

Extensions

Extended by Nathaniel Johnston, May 18 2011