A167782 Numbers that are repdigits with length > 2 in some base.

0, 7, 13, 15, 21, 26, 31, 40, 42, 43, 57, 62, 63, 73, 80, 85, 86, 91, 93, 111, 114, 121, 124, 127, 129, 133, 146, 156, 157, 170, 171, 172, 182, 183, 211, 215, 219, 222, 228, 241, 242, 255, 259, 266, 273, 285, 292, 307, 312, 314, 333, 341, 342, 343, 364, 365, 366

Offset: 1

Author

Andrew Weimholt, Nov 12 2009

Keywords

• nonn
• base

Comments

Definition requires "length > 2" because all numbers n > 2 are trivially represented as "11" in base n-1.

0 included at the suggestion of Franklin T. Adams-Watters (and others) as 0 = 000 in any base.

Examples

			26 is a term because 26_10 = 222_3.
		

Links

• Vojtech Strnad, Table of n, a(n) for n = 1..10000
• Wolfram Demonstrations Project, Mixed Radix Number Representations [From _Daniel Forgues_, Nov 13 2009]

Crossrefs

Cf. A010785 (Repdigits (base 10)).

Cf. A167783 (Numbers that are repdigits with length > 2 in more than one base).

Cf. A053696 (Numbers which are repunits in some base).

Cf. A158235 (Numbers n whose square can be represented as a repdigit number in some base < n).

Programs

PARI

/* In PARI versions < 2.6, define: digits(n,b) = if(n=b^2+b+1,d=digits(n,b);if(is_repdigit(d),print(n," = ",d," base ",b));b++)) \\ Michael B. Porter