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 A140975 #17 Jan 09 2024 11:09:35 %S A140975 1,3,8,8,9,1,6,6,7,9,4,4,5,7,2,2,3,5,0,0,1,3,8,8,9,1,6,6,7,9,4,4,5,7, %T A140975 2,2,3,5,0,0,1,3,8,8,9,1,6,6,7,9,4,4,5,7,2,2,3,5,0,0 %N A140975 Period length 20: repeat 1, 3, 8, 8, 9, 1, 6, 6, 7, 9, 4, 4, 5, 7, 2, 2, 3, 5, 0, 0. %C A140975 The period contains each digit from 0 to 9 twice. %H A140975 <a href="/index/Rec#order_19">Index entries for linear recurrences with constant coefficients</a>, signature (1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1). %F A140975 a(n) = A011377(n) mod 10. %F A140975 a(n) = +a(n-1) -a(n-2) +a(n-3) -a(n-4) +a(n-5) -a(n-6) +a(n-7) -a(n-8) +a(n-9) -a(n-10) +a(n-11) -a(n-12) +a(n-13) -a(n-14) +a(n-15) -a(n-16) +a(n-17) -a(n-18) +a(n-19). %F A140975 G.f.: ( -1 -2*x -6*x^2 -7*x^4 -12*x^6 -13*x^8 +4*x^9 -8*x^10 -9*x^12 +2*x^13 -5*x^16 -2*x^3 +4*x^11 +2*x^15 +6*x^5 +6*x^7 -4*x^14 ) / ( (x-1) *(1+x^2) *(1+x+x^2+x^3+x^4) *(1-x+x^2-x^3+x^4) *(1-x^2+x^4-x^6+x^8) ). - _R. J. Mathar_, Jul 08 2011 %Y A140975 Cf. A011377. %K A140975 nonn,easy,less %O A140975 0,2 %A A140975 _Paul Curtz_, Jul 28 2008