A209929 Smallest digit of all divisors of n.

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.

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for characteristic functions

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

Adjacent sequences: A209926 A209927 A209928 * A209930 A209931 A209932

Keyword

nonn,base,less

Author

Jaroslav Krizek, Mar 20 2012

Extensions

More terms from Antti Karttunen, Dec 07 2017

Status

approved