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

1,1

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 A356396

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