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 A113876 #21 Jul 08 2024 21:34:08 %S A113876 1,5,13,77,205,1229,3277,19661,52429,314573,838861,5033165,13421773, %T A113876 80530637,214748365,1288490189,3435973837,20615843021,54975581389, %U A113876 329853488333,879609302221,5277655813325,14073748835533,84442493013197,225179981368525,1351079888211149 %N A113876 a(n) = a(n-1) + 2^(k(n)), where k(n) is the n-th term of the sequence formed by k(1)=0 together with the numbers A042964. %H A113876 Vincenzo Librandi, <a href="/A113876/b113876.txt">Table of n, a(n) for n = 1..300</a> %H A113876 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,16,-16). %F A113876 G.f.: (1+x-8*x^2)/(2*(-1+x)*(-1+4*x)*(1+4*x)). - _Vaclav Kotesovec_, Nov 28 2012 %F A113876 a(n) = (4 + (-4)^n + 5*4^n)/20. - _Gerry Martens_, May 26 2024 %o A113876 (PARI) a(n)=(4+(-4)^n+5*4^n)/20 \\ _Charles R Greathouse IV_, Jul 08 2024 %Y A113876 Cf. A042964, A099974, A112627, A080355, A080567, A099969, A099970, A099971. %K A113876 nonn,easy %O A113876 1,2 %A A113876 _Artur Jasinski_, Jan 27 2006 %E A113876 Edited with better definition and offset corrected by _Omar E. Pol_, Jan 08 2009