login
a(n) is the n-th number m such that m^2 divides n^m - 1 (or 0 if m does not exist).
1

%I #11 Mar 24 2020 22:31:07

%S 1,0,4,903,12,776119592182705,12,42931441,136,27486820443,60,

%T 107342336783,84

%N a(n) is the n-th number m such that m^2 divides n^m - 1 (or 0 if m does not exist).

%F a(n) = A333500(n,n).

%o (PARI) {a(n) = if(n==2, 0, my(cnt=0, k=0); while(cnt<n, k++; if(Mod(n, k^2)^k==1, cnt++)); k)}

%Y Main diagonal of A333500.

%Y Cf. A127106, A127100, A128405, A333433.

%K nonn,more

%O 1,3

%A _Seiichi Manyama_, Mar 24 2020