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A160754 Numbers k such that k, 2k, 3k and 4k use the same number of characters when expressed in Roman numerals. 0

%I #24 Jan 09 2020 12:06:27

%S 36,153,315,351,360,448,736,1386

%N Numbers k such that k, 2k, 3k and 4k use the same number of characters when expressed in Roman numerals.

%C This sequence is complete up to 3999.

%e 1*36 = 36 = XXXVI,

%e 2*36 = 72 = LXXII,

%e 3*36 = 108 = CVIII,

%e 4*36 = 144 = CXLIV,

%e so 36 is a term;

%e 1*153 = 153 = CLIII,

%e 2*153 = 306 = CCCVI,

%e 3*153 = 459 = CDLIX,

%e 4*153 = 612 = DCXII,

%e so 153 is a term.

%p 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)) and length(convert(n, roman)) = length(convert(4*n, roman)))then printf("%d, ", n): fi: od: # _Nathaniel Johnston_, May 18 2011

%Y See A006968 for the basic underlying sequence.

%K nonn,easy

%O 1,1

%A _Claudio Meller_, May 25 2009

%E a(8) from _Nathaniel Johnston_, May 18 2011

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Last modified March 28 14:02 EDT 2024. Contains 371254 sequences. (Running on oeis4.)