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a(n) = 7^n mod 1000.
1

%I #11 Sep 08 2022 08:46:03

%S 1,7,49,343,401,807,649,543,801,607,249,743,201,407,849,943,601,207,

%T 449,143,1,7,49,343,401,807,649,543,801,607,249,743,201,407,849,943,

%U 601,207,449,143,1,7,49,343,401,807,649,543,801,607,249,743,201,407,849,943,601,207,449,143,1

%N a(n) = 7^n mod 1000.

%C Period = 20.

%H Vincenzo Librandi, <a href="/A216129/b216129.txt">Table of n, a(n) for n = 0..1000</a>

%t PowerMod[7, Range[0, 100], 1000] (* _Vincenzo Librandi_, Aug 16 2016 *)

%o (PARI) for(i=0, 100, print(7^i%1000" "))

%o (Magma) [Modexp(7, n, 1000): n in [0..110]]; // _Vincenzo Librandi_, Aug 16 2016

%Y Cf. A001903, A014390.

%K nonn,easy

%O 0,2

%A _V. Raman_, Sep 01 2012

%E a(0) = 1 prepended and offset changed by _Vincenzo Librandi_, Aug 16 2016