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 A130917 #11 May 06 2024 12:38:06 %S A130917 1,1,2,4,8,16,23,28,29,31,35,43,50,55,56,58,62,70,77,82,83,85,89,97, %T A130917 104,109,110,112,116,124,131,136,137,139,143,151,158,163,164,166,170, %U A130917 178,185,190,191,193,197,205 %N A130917 a(n) is the sum of the digital roots of all of the previous terms. %C A130917 Essentially identical to A007612, which is the main entry for this sequence. - _N. J. A. Sloane_, Aug 25 2007 %H A130917 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,-1,2,-1). %F A130917 G.f.: x*(5*x^5+x^4+2*x^3+x^2-x+1) / ((x-1)^2*(x+1)*(x^2-x+1)). - _Colin Barker_, Jan 17 2014 %e A130917 a(8) = 28 because the digital roots of the previous terms are 1,1,2,4,8,7 and 5 and 1+1+2+4+8+7+5 = 28 %o A130917 (PARI) Vec(x*(5*x^5+x^4+2*x^3+x^2-x+1)/((x-1)^2*(x+1)*(x^2-x+1)) + O(x^100)) \\ _Colin Barker_, Jan 17 2014 %Y A130917 Cf. A007612. %K A130917 easy,nonn,base %O A130917 1,3 %A A130917 Stephen Casey (hexomino(AT)gmail.com), Aug 23 2007