A357111 - OEIS

%I #23 Sep 26 2022 02:05:34

%S 1,1,3,1,5,3,7,1,9,1,11,3,13,7,15,1,17,9,19,1,1,11,23,3,25,13,27,7,29,

%T 3,31,1,3,17,35,9,37,19,39,1,41,1,43,11,45,23,47,3,49,5,51,13,53,27,

%U 55,7,57,29,59,3,61,31,3,1,65,3,67,17,23,7,71,9,73,37,75

%N For n >= 1, a(n) = n / A076775(n).

%H Robert Israel, <a href="/A357111/b357111.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = 1 for n = A076775(A032533(k)).

%F a(n) != n for n = A354837(k), a(n) = n for all other odd n.

%F a(n) != A000265(n) for n = 10*k and for n = 2^r * A354837(k), r >= 0, k >= 1.

%e a(12) = 12 / A076775(12) = 3.

%p f:= proc(n) local L,i;

%p   L:= convert(n,base,2);

%p   n/igcd(n,add(10^(i-1)*L[i],i=1..nops(L)));

%p end proc:

%p map(f, [$1..100]); # _Robert Israel_, Sep 11 2022

%t a[n_] := n / GCD[n, FromDigits@IntegerDigits[n, 2]]; Array[a, 100] (* _Amiram Eldar_, Sep 11 2022 *)

%o (Python)

%o from math import gcd

%o def A357111(n): return n//gcd(n,int(bin(n)[2:])) # _Chai Wah Wu_, Sep 12 2022

%Y Cf. A000265, A032533, A076775, A354837.

%K nonn,base,look

%O 1,3

%A _Ctibor O. Zizka_, Sep 11 2022