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A270035 a(n) is the smallest b for which the base-b representation of n contains at least one 9 (or 0 if no such base exists). 11
0, 0, 0, 0, 0, 0, 0, 0, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 10, 21, 11, 23, 12, 25, 13, 27, 14, 29, 10, 31, 16, 11, 17, 35, 12, 37, 19, 13, 10, 41, 14, 43, 11, 15, 23, 47, 12, 49, 10, 17, 13, 53, 18, 11, 14, 19, 29, 59, 10, 61, 31, 21, 16, 13, 11, 67, 17, 23, 10, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,9
COMMENTS
a(n) > 0 for n >= 19 since 19 is n written in base n-9.
The only perfect k-th powers (k >= 2) that can appear in this sequence are m^k with 2 <= m <= 9 and k a prime number.
LINKS
MATHEMATICA
Table[SelectFirst[Range[10, 1200], DigitCount[n, #, 9] > 0 &], {n, 19, 120}] (* Michael De Vlieger, Mar 10 2016, Version 10 *)
PROG
(PARI) a(n) = if ((n<19) && (n!=9), 0, my(b=10); while(!vecsearch(Set(digits(n, b)), 9), b++); b); \\ Michel Marcus, Mar 10 2016
CROSSREFS
Sequence in context: A058472 A058474 A285476 * A228636 A306758 A340983
KEYWORD
nonn,base
AUTHOR
Nathan Fox, Mar 08 2016
STATUS
approved

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Last modified February 28 19:33 EST 2024. Contains 370400 sequences. (Running on oeis4.)