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 A017641 #39 Apr 04 2025 10:20:31
%S A017641 10,22,34,46,58,70,82,94,106,118,130,142,154,166,178,190,202,214,226,
%T A017641 238,250,262,274,286,298,310,322,334,346,358,370,382,394,406,418,430,
%U A017641 442,454,466,478,490,502,514,526,538,550,562,574,586,598,610,622,634
%N A017641 a(n) = 12*n + 10.
%C A017641 Exponents e such that x^e + x^2 - 1 is reducible.
%C A017641 If Y is a 4-subset of an (2n+1)-set X then, for n>=3, a(n-2) is the number of 3-subsets of X having at least two elements in common with Y. - _Milan Janjic_, Dec 16 2007
%H A017641 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>.
%H A017641 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A017641 A030132(a(n)) = 9. - _Reinhard Zumkeller_, Jul 04 2007
%F A017641 G.f.: 2*(5 + x)/(1 - x)^2. - _Stefano Spezia_, May 09 2021
%F A017641 Sum_{n>=0} (-1)^n/a(n) = Pi/12 - sqrt(3)*log(2 + sqrt(3))/12. - _Amiram Eldar_, Dec 12 2021
%F A017641 From _Elmo R. Oliveira_, Apr 04 2025: (Start)
%F A017641 E.g.f.: 2*exp(x)*(5 + 6*x).
%F A017641 a(n) = 2*A016969(n).
%F A017641 a(n) = 2*a(n-1) - a(n-2) for n >= 2. (End)
%t A017641 Range[10, 1000, 12] (* _Vladimir Joseph Stephan Orlovsky_, May 29 2011 *)
%o A017641 (PARI) a(n)=12*n+10 \\ _Charles R Greathouse IV_, Jul 10 2016
%Y A017641 Cf. A008594, A016969, A017533, A017545, A017593, A030132.
%K A017641 nonn,easy
%O A017641 0,1
%A A017641 _N. J. A. Sloane_