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 A075683 #11 Jun 21 2024 15:23:19
%S A075683 2,17,20,22,25,28,31,34,37,40,43,46,49,52,55,58,61,64,67,70,73,76,79,
%T A075683 82,85,88,91,94,97,100,103,106,109,112,115,118,121,124,127,130,133,
%U A075683 136,139,142,145,148,151,154,157,160,163,166,169,172,175,178,181,184,187,190,193,196
%N A075683 2nd differences of A075681.
%H A075683 G. C. Greubel, <a href="/A075683/b075683.txt">Table of n, a(n) for n = 1..1000</a>
%H A075683 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A075683 From _G. C. Greubel_, Jan 02 2024: (Start)
%F A075683 a(n) = 2*a(n-1) - a(n-2), for n >= 6.
%F A075683 a(n) = A075681(n+2) - 2*A075681(n+1) + A075681(n).
%F A075683 a(n) = A075682(n+1) - A075682(n).
%F A075683 a(n) = 3*n + 10 - 11*[n=1] + [n=2] + [n=3].
%F A075683 G.f.: x*(2 + 13*x - 12*x^2 - x^3 + x^4)/(1 - x)^2.
%F A075683 E.g.f.: (10 + 3*x)*exp(x) - 10 - 11*x + x^2/2! + x^3/3!. (End)
%t A075683 Join[{2,17,20}, 10+3*Range[4,70]] (* _G. C. Greubel_, Jan 02 2024 *)
%o A075683 (Magma) [2,17,20] cat [3*n+10: n in [4..70]]; // _G. C. Greubel_, Jan 02 2024
%o A075683 (SageMath) [2,17,20]+[3*n+10 for n in range(4,71)] # _G. C. Greubel_, Jan 02 2024
%Y A075683 Cf. A075681, A075682.
%K A075683 nonn,easy
%O A075683 1,1
%A A075683 _Jon Perry_, Oct 12 2002
%E A075683 Terms a(11) onward added by _G. C. Greubel_, Jan 02 2024