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 A003222 #31 Mar 06 2025 20:29:10 %S A003222 2,10,108,982,8120,65426,524132,4194094,33554160,268435114,2147483228, %T A003222 17179868678,137438952872,1099511627074,8796093021396,70368744176734, %U A003222 562949953420256,4503599627369306,36028797018962636,288230376151710262,2305843009213692312,18446744073709549810 %N A003222 a(n) = 2^(3*n+1) - 2*n*(2*n+1). %H A003222 Vincenzo Librandi, <a href="/A003222/b003222.txt">Table of n, a(n) for n = 0..200</a> %H A003222 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (11,-27,25,-8). %F A003222 a(n) = A013730(n) - A002943(n). %F A003222 From _R. J. Mathar_, May 05 2010: (Start) %F A003222 a(n) = 11*a(n-1) - 27*a(n-2) + 25*a(n-3) - 8*a(n-4). %F A003222 G.f.: 2*(1 - 6*x + 26*x^2 + 7*x^3)/((8*x-1)*(x-1)^3). (End) %F A003222 E.g.f.: 2*exp(x)*(exp(7*x) - x*(3 + 2*x)). - _Elmo R. Oliveira_, Mar 06 2025 %o A003222 (Magma) [2^(3*n+1)-2*n*(2*n+1): n in [0..20]]; // _Vincenzo Librandi_, Jun 26 2011 %o A003222 (PARI) a(n) = 2^(3*n+1)-2*n*(2*n+1); \\ _Altug Alkan_, Sep 21 2018 %Y A003222 Cf. A002943, A013730. %K A003222 nonn,easy %O A003222 0,1 %A A003222 _N. J. A. Sloane_