A290869 Numbers that are repdigits with length > 2 in more than two bases.

4095, 32767, 65535, 67053, 262143, 265720, 531440, 1048575, 2097151, 4381419, 5592405, 7174453, 9808617, 11184810, 13938267, 14348906, 16777215, 19617234, 21523360, 29425851, 39234468, 43046720, 48686547, 49043085, 58851702, 61035156, 68660319, 71270178

Offset: 1

Author

Michel Marcus, Aug 13 2017

Keywords

• nonn
• base

Comments

Most of the terms of A167783 are repdigits with length > 2 in only two bases.

For any b > 1 and k > 2, b^(4*k)-1 is a repdigit with length > 2 in bases b, b^2 and b^4; hence this sequence is infinite. - Rémy Sigrist, Aug 19 2017

Examples

			67053 is a repdigit with more than 2 digits in three bases: [31,31,31]_46, [21,21,21]_56, [3,3,3]_149.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..777
• Rémy Sigrist, C# program for A290869
• Rémy Sigrist, C++ program for A290869

Crossrefs

Subsequence of A167783.

Programs

PARI

isok(n)=my(nb = 0); for (b=2, n-1, d = digits(n, b); if ((#d > 2) && (#Set(d) == 1), nb++); if (nb > 2, return (1)); ); return (0);
(C#) See Links section.
(C++) See Links section.

Extensions

More terms from Giovanni Resta, Aug 13 2017