A225450 - OEIS

%I #13 Jul 19 2020 19:23:01

%S 7,6,3,4,0,1,9,6,8,0,7,7,0,7,5,0,6,8,6,0,5,9,2,5,6,3,2,1,3,5,3,1,8,2,

%T 2,8,6,1,1,9,8,2,1,5,3,9,6,9,8,9,9,7,1,9,7,5,6,5,1,7,0,7,6,4,4,5,8,6,

%U 4,6,8,9,2,9,8,8,3,2,0,0,1,8,2,7,9,1,5,8,6,8,2,5,6,4,6,2,9,3,5,7

%N 10-adic integer x such that x^7 == (2*(10^n-1)/9)+1 mod 10^n for all n.

%C This is the 10's complement of A225441.

%H Robert Israel, <a href="/A225450/b225450.txt">Table of n, a(n) for n = 1..10000</a>

%e 7^7 == 3 (mod 10).

%e 67^7 == 23 (mod 100).

%e 367^7 == 223 (mod 1000).

%e 4367^7 == 2223 (mod 10000).

%e 4367^7 == 22223 (mod 100000).

%e 104367^7 == 222223 (mod 1000000).

%p op([1,3],padic:-evalp(RootOf(x^7-7/9,x),10,202)); # _Robert Israel_, Feb 05 2019

%o (PARI) n=0;for(i=1,100,m=(2*(10^i-1)/9)+1;for(x=0,9,if(((n+(x*10^(i-1)))^7)%(10^i)==m,n=n+(x*10^(i-1));print1(x", ");break)))

%Y Cf. A225441.

%K nonn,base

%O 1,1

%A _Aswini Vaidyanathan_, May 11 2013