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A270832 Number of bases in which n is written using more than 1 digit, all of which are distinct. 2
0, 1, 1, 1, 2, 3, 4, 4, 5, 5, 8, 7, 9, 9, 11, 10, 12, 12, 16, 14, 16, 16, 18, 17, 19, 19, 22, 22, 24, 23, 25, 24, 27, 27, 30, 27, 30, 32, 34, 32, 35, 34, 36, 37, 38, 38, 41, 39, 42, 41, 45, 45, 48, 47, 48, 48, 49, 51, 53, 48, 53, 54, 55, 53, 57, 58, 60, 60, 63, 62 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

n/2 - 1 <= a(n) < n.

a(n) is not always <= n - sqrt(n) + 1. Counterexample: for n = 1000000, a(n) = 999911 > 999001 = n - sqrt(n) + 1. - Lucas O. Wagner, Jul 27 2019

LINKS

Jinyuan Wang, Table of n, a(n) for n = 1..10000

EXAMPLE

a(5) = 2 because 5 equals 10 in base 5, 12 in base 3. In base 2 (101) and base 4 (11) there are repeated digits, in base > 5 it is only one digit long.

MATHEMATICA

Table[Count[Function[b, AllTrue[DigitCount[n, b], # <= 1 &]] /@ Range[2, n], True], {n, 70}] (* Michael De Vlieger, Mar 24 2016, Version 10 *)

PROG

(PARI) a(n) = sum(b=2, n, v = digits(n, b); (#v > 1) && (#v == #Set(v))); \\ Michel Marcus, Mar 24 2016

CROSSREFS

Sequence in context: A216411 A110532 A049987 * A257646 A051898 A092032

Adjacent sequences:  A270829 A270830 A270831 * A270833 A270834 A270835

KEYWORD

nonn,base

AUTHOR

André Engels, Mar 23 2016

STATUS

approved

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Last modified August 10 16:56 EDT 2020. Contains 336381 sequences. (Running on oeis4.)