This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A000855 #36 Aug 09 2025 12:51:36 %S A000855 1,2,4,8,16,32,64,28,56,12,24,48,96,92,84,68,36,72,44,88,76,52,4,8,16, %T A000855 32,64,28,56,12,24,48,96,92,84,68,36,72,44,88,76,52,4,8,16,32,64,28, %U A000855 56,12,24,48,96,92,84,68,36,72,44,88,76,52,4,8,16,32,64,28 %N A000855 Final two digits of 2^n. %C A000855 Has period 20 (starting with a(2)=4). %H A000855 T. D. Noe, <a href="/A000855/b000855.txt">Table of n, a(n) for n = 0..1000</a> %H A000855 <a href="/index/Fi#final">Index entries for sequences related to final digits of numbers</a> %H A000855 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,0,-1,1). %F A000855 G.f.: -(50*x^12 +25*x^11 +13*x^10 -44*x^9 +28*x^8 -36*x^7 +32*x^6 +16*x^5 +8*x^4 +4*x^3 +2*x^2 +x +1) / ((x -1)*(x^2 +1)*(x^8 -x^6 +x^4 -x^2 +1)). - _Colin Barker_, Dec 01 2014 %F A000855 For n > 13: a(n) = a(n-1) - a(n-10) + a(n-11). - Ray Chandler, Aug 09 2025 %t A000855 PowerMod[2,Range[0,60],100] (* _Harvey P. Dale_, Jan 05 2012 *) %o A000855 (PARI) a(n)=lift(Mod(2,100)^n) \\ _Charles R Greathouse IV_, Dec 28 2012 %Y A000855 Cf. A000689, A126605. %K A000855 nonn,base,easy %O A000855 0,2 %A A000855 _N. J. A. Sloane_