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A167782 Numbers that are repdigits with length > 2 in some base. 15
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
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.
LINKS
Wolfram Demonstrations Project, Mixed Radix Number Representations [From Daniel Forgues, Nov 13 2009]
EXAMPLE
26 is a term because 26_10 = 222_3.
PROG
(PARI) digits(n, b) = if(n<b, [n], concat(digits(floor(n/b), b), n%b))
is_repdigit(d) = {local(a, r); r=1; a=d[1]; for(i=2, matsize(d)[2], if(a!=d[i], r=0)); r}
for(n=1, 1200, b=2; while(n>=b^2+b+1, d=digits(n, b); if(is_repdigit(d), print(n, " = ", d, " base ", b)); b++)) \\ Michael B. Porter
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).
Sequence in context: A330431 A349751 A349752 * A326380 A257521 A053696
KEYWORD
nonn,base
AUTHOR
Andrew Weimholt, Nov 12 2009
STATUS
approved

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)