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A209929
Smallest digit of all divisors of n.
4
1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0
OFFSET
1
COMMENTS
Also smallest digit of concatenation of all divisors of n (A037278, A176558).
Also characteristic function of numbers n such that smallest digit among all divisors of n is 1 (A209931), in other words, numbers whose divisor set does not contain any number with a nonleading zero.
Sequence is not the same as A168184, first deviation is at a(101): A168184(101) = 1, a(101) = 0.
Sequence is not the same as A168046, first deviation is at a(214): A168046(214) = 1, a(214) = 0.
EXAMPLE
a(214) = 0 because smallest digit of all divisors of 214 (1, 2, 107, 214) is 0.
MATHEMATICA
Table[Min[Flatten[IntegerDigits/@Divisors[n]]], {n, 100}] (* Harvey P. Dale, Jul 20 2015 *)
PROG
(PARI)
A168046(n) = if(!n, 0, !!(vecsort(digits(n), , 8)[1]));
A209929(n) = { my(divs=divisors(n)); factorback(vector(numdiv(n), i, A168046(divs[i]))); }; \\ Antti Karttunen, Dec 07 2017
CROSSREFS
Cf. A168046, A209928 (largest digit of all divisors of n), A054054 (smallest digit of n).
Sequence in context: A137794 A357731 A336546 * A336556 A105586 A202022
KEYWORD
nonn,base,less
AUTHOR
Jaroslav Krizek, Mar 20 2012
EXTENSIONS
More terms from Antti Karttunen, Dec 07 2017
STATUS
approved