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A209928 Largest digit of all divisors of n. 6
1, 2, 3, 4, 5, 6, 7, 8, 9, 5, 1, 6, 3, 7, 5, 8, 7, 9, 9, 5, 7, 2, 3, 8, 5, 6, 9, 8, 9, 6, 3, 8, 3, 7, 7, 9, 7, 9, 9, 8, 4, 7, 4, 4, 9, 6, 7, 8, 9, 5, 7, 6, 5, 9, 5, 8, 9, 9, 9, 6, 6, 6, 9, 8, 6, 6, 7, 8, 9, 7, 7, 9, 7, 7, 7, 9, 7, 9, 9, 8, 9, 8, 8, 8, 8, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also largest digit of concatenation of all divisors  of n (A037278, A176558). - Jaroslav Krizek

a(n) = 9 for almost all n. - Charles R Greathouse IV, Mar 20 2012

With an offset of 1 rather than 0, A016186 tells us how many integers among the first 10^n have 9s among their digits, and those numbers are therefore guaranteed to index a 9 in this sequence. More interesting of course are those numbers that don't have a 9 in their own digits but do have a 9 among the digits of their nontrivial divisors. - Alonso del Arte, Mar 23 2012

LINKS

Table of n, a(n) for n=1..86.

EXAMPLE

a(12) = 6 because digit 6 is largest digit of all divisors of 12: (1, 2, 3, 4, 6, 12).

MATHEMATICA

Flatten[Table[Take[Sort[Flatten[IntegerDigits[Divisors[n]]]], -1], {n, 100}]] (* Alonso del Arte, Mar 23 2012 *)

PROG

(PARI) a(n)=my(t); fordiv(n, d, t=max(t, vecmax(eval(Vec(Str(d))))); if(t>8, return(t))); t \\Charles R Greathouse IV, Mar 20 2012

CROSSREFS

Cf. A054055 (largest digit of n).

Sequence in context: A028899 A081595 A122644 * A028900 A081596 A061500

Adjacent sequences:  A209925 A209926 A209927 * A209929 A209930 A209931

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, Mar 20 2012

STATUS

approved

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Last modified October 27 23:26 EDT 2020. Contains 338047 sequences. (Running on oeis4.)