login
a(n) is the least divisor u of A331221(n) such that the decimal representations of u and of A331221(n)/u have the same number of digits d for d = 0..9.
3

%I #10 Jan 13 2020 18:25:57

%S 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,12,16,17,18,19,20,13,21,22,23,14,

%T 24,25,26,27,23,15,28,29,30,31,16,24,32,33,34,17,35,36,25,37,38,18,34,

%U 39,40,26,41,19,42,43,35,44,27,45,46,47,36,28,48,49,45

%N a(n) is the least divisor u of A331221(n) such that the decimal representations of u and of A331221(n)/u have the same number of digits d for d = 0..9.

%H Rémy Sigrist, <a href="/A331270/b331270.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) * A331271(n) = A331221(n).

%o (PARI) b=10; k=67; for (n=1, oo, fordiv (n, u, if (vecsort(digits(u,b))==vecsort(digits(n/u,b)), print1 (u", "); break (if (k--, 1, 2)))))

%Y Cf. A331221, A331271.

%K nonn,base

%O 1,2

%A _Rémy Sigrist_, Jan 13 2020