A070462 - OEIS

%I #15 Dec 18 2023 13:06:22

%S 0,1,4,9,16,25,36,9,24,1,20,1,24,9,36,25,16,9,4,1,0,1,4,9,16,25,36,9,

%T 24,1,20,1,24,9,36,25,16,9,4,1,0,1,4,9,16,25,36,9,24,1,20,1,24,9,36,

%U 25,16,9,4,1,0,1,4,9,16,25,36,9,24,1,20,1,24,9,36,25,16,9,4,1,0,1,4,9,16

%N a(n) = n^2 mod 40.

%H G. C. Greubel, <a href="/A070462/b070462.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_20">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

%F a(n) = a(n-20). - _G. C. Greubel_, Mar 25 2016

%t Table[Mod[n^2,40],{n,0,200}] (* _Vladimir Joseph Stephan Orlovsky_, Apr 27 2011 *)

%t PowerMod[Range[0,90],2,40] (* _Harvey P. Dale_, Oct 20 2013 *)

%o (PARI) a(n)=n^2%40 \\ _Charles R Greathouse IV_, Apr 06 2016

%Y Cf. A070456, A070457.

%K nonn,easy

%O 0,3

%A _N. J. A. Sloane_, May 12 2002