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 A051936 #66 Jun 12 2024 11:46:28
%S A051936 1,6,12,19,27,36,46,57,69,82,96,111,127,144,162,181,201,222,244,267,
%T A051936 291,316,342,369,397,426,456,487,519,552,586,621,657,694,732,771,811,
%U A051936 852,894,937,981,1026,1072,1119,1167,1216,1266,1317,1369,1422,1476
%N A051936 Truncated triangular numbers: a(n) = n*(n+1)/2 - 9.
%C A051936 Equals binomial transform of [1, 5, 1, 0, 0, 0, ...]. - _Gary W. Adamson_, Apr 30 2008
%C A051936 Numbers m > 0 such that 8m+73 is a square. - _Bruce J. Nicholson_, Jul 29 2017
%H A051936 Reinhard Zumkeller, <a href="/A051936/b051936.txt">Table of n, a(n) for n = 4..10000</a>
%H A051936 Margaret Bayer, Mark Denker, Marija Jelić Milutinović, Rowan Rowlands, Sheila Sundaram, and Lei Xue, <a href="https://arxiv.org/abs/2304.13675">Topology of Cut Complexes of Graphs</a>, arXiv:2304.13675 [math.CO], 2023.
%H A051936 Pratiksha Chauhan, Samir Shukla, and Kumar Vinayak, <a href="https://arxiv.org/abs/2406.01979">3-Cut Complexes of Squared Cycle Graphs</a>, arXiv:2406.01979 [math.CO], 2024. See p. 2.
%H A051936 Cecilia Rossiter, <a href="http://web.archive.org/web/20130515133733/http://noticingnumbers.net/300SeriesCube.htm">Depictions, Explorations and Formulas of the Euler/Pascal Cube</a>. [Wayback Machine copy]
%H A051936 Cecilia Rossiter, <a href="/A005581/a005581.pdf">Depictions, Explorations and Formulas of the Euler/Pascal Cube</a> [Cached copy, May 15 2013]
%H A051936 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A051936 G.f.: x^4*(-1-3*x+3*x^2) / (x-1)^3.
%F A051936 a(n) = n + a(n-1) for n>4, a(4)=1. - _Vincenzo Librandi_, Aug 06 2010
%F A051936 a(n) = 2*A000217(n-3) - A000217(n-6), with A000217(-2)=1, A000217(-1)=0. - _Bruno Berselli_, Oct 13 2016
%F A051936 Sum_{n>=4} 1/a(n) = 53/72 + 2*Pi*tan(sqrt(73)*Pi/2)/sqrt(73). - _Amiram Eldar_, Dec 13 2022
%e A051936 Illustration of the initial terms:
%e A051936 .
%e A051936 . . .
%e A051936 . . . o o o
%e A051936 . . o o o o o o o
%e A051936 . o . . o o . . o o o .
%e A051936 . . . . . . o . . . . o o . .
%e A051936 ----------------------------------------------------------------------
%e A051936 1 6 12
%e A051936 ----------------------------------------------------------------------
%e A051936 - _Bruno Berselli_, Oct 13 2016
%t A051936 Table[n*(n + 1)/2 - 9, {n, 4, 60}] (* _Stefan Steinerberger_, Mar 25 2006 *)
%t A051936 k = 4; NestList[(k++; # + k) &, 1, 45] (* _Robert G. Wilson v_, Feb 02 2011 *)
%t A051936 Drop[Accumulate[Range[60]]-9,3] (* _Harvey P. Dale_, Jan 16 2012 *)
%o A051936 (Haskell)
%o A051936 a051936 = (subtract 9) . a000217
%o A051936 a051936_list = scanl (+) 1 [5..]
%o A051936 -- _Reinhard Zumkeller_, Oct 25 2012
%o A051936 (PARI) a(n)=n*(n+1)/2-9 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A051936 Cf. A000217.
%K A051936 nonn,nice,easy
%O A051936 4,2
%A A051936 Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 21 1999