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 A017233 #60 Apr 10 2025 17:13:39
%S A017233 6,15,24,33,42,51,60,69,78,87,96,105,114,123,132,141,150,159,168,177,
%T A017233 186,195,204,213,222,231,240,249,258,267,276,285,294,303,312,321,330,
%U A017233 339,348,357,366,375,384,393,402,411,420,429,438,447,456,465,474,483
%N A017233 a(n) = 9*n + 6.
%C A017233 General form: (q*n-1)*q, cf. A017233 (q=3), A098502 (q=4). - _Vladimir Joseph Stephan Orlovsky_, Feb 16 2009
%C A017233 Numbers whose digital root is 6; that is, A010888(a(n)) = 6. (Ball essentially says that Iamblichus (circa 350) announced that a number equal to the sum of three integers 3*n, 3*n - 1, and 3*n - 2 has 6 as what is now called the number's digital root.) - _Rick L. Shepherd_, Apr 01 2014
%D A017233 W. W. R. Ball, A Short Account of the History of Mathematics, Sterling Publishing Company, Inc., 2001 (Facsimile Edition) [orig. pub. 1912], pages 110-111.
%H A017233 Vincenzo Librandi, <a href="/A017233/b017233.txt">Table of n, a(n) for n = 0..5000</a>
%H A017233 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>.
%H A017233 Luis Manuel Rivera, <a href="http://arxiv.org/abs/1406.3081">Integer sequences and k-commuting permutations</a>, arXiv preprint arXiv:1406.3081 [math.CO], 2014-2015.
%H A017233 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A017233 G.f.: 3*(2+x)/(x-1)^2. - _R. J. Mathar_, Mar 20 2018
%F A017233 Sum_{n>=0} (-1)^n/a(n) = sqrt(3)*Pi/27 - log(2)/9. - _Amiram Eldar_, Dec 12 2021
%F A017233 E.g.f.: 3*exp(x)*(2 + 3*x). - _Stefano Spezia_, Dec 07 2024
%F A017233 From _Elmo R. Oliveira_, Apr 10 2025: (Start)
%F A017233 a(n) = 3*A016789(n) = A019557(n+1)/2.
%F A017233 a(n) = 2*a(n-1) - a(n-2). (End)
%t A017233 Range[6, 1000, 9] (* _Vladimir Joseph Stephan Orlovsky_, May 28 2011 *)
%t A017233 LinearRecurrence[{2,-1},{6,15},60] (* _Harvey P. Dale_, Feb 01 2014 *)
%o A017233 (Magma) [9*n+6: n in [0..60]]; // _Vincenzo Librandi_, Jul 24 2011
%o A017233 (PARI) a(n)=9*n+6 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A017233 Cf. A008585, A008591, A010888, A016789, A017209, A017221, A017233, A019557, A098502.
%K A017233 nonn,easy
%O A017233 0,1
%A A017233 David J. Horn and Laura Krebs Gordon (lkg615(AT)verizon.net), 1985