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 A196508 #21 Apr 04 2024 09:49:45 %S A196508 0,4,20,76,252,764,2172,5884,15356,38908,96252,233468,557052,1310716, %T A196508 3047420,7012348,15990780,36175868,81264636,181403644,402653180, %U A196508 889192444,1954545660,4278190076,9328132092,20266876924,43889197052 %N A196508 a(n) = 2^n*(n^2 - n + 4)-4. %D A196508 Jolley, Summation of Series, Dover (1961), eq. (46) on page 8. %H A196508 Vincenzo Librandi, <a href="/A196508/b196508.txt">Table of n, a(n) for n = 0..3000</a> %H A196508 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (7,-18,20,-8) %F A196508 a(n) = 2*2 + 4*4 + 7*8 + 11*16 + 16*32 + ... (n terms of A000124*A000079). %F A196508 a(n) = 4*A053545(n). %F A196508 G.f.: 4*x*(1 - 2*x + 2*x^2) / ( (x-1)*(2*x-1)^3 ). %o A196508 (Magma) [2^n*(n^2-n+4)-4: n in [0..30]]; // _Vincenzo Librandi_, Oct 05 2011 %K A196508 nonn,easy %O A196508 0,2 %A A196508 _R. J. Mathar_, Oct 03 2011