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 A154617 #22 Dec 15 2024 12:58:28 %S A154617 0,11,66,165,308,495,726,1001,1320,1683,2090,2541,3036,3575,4158,4785, %T A154617 5456,6171,6930,7733,8580,9471,10406,11385,12408,13475,14586,15741, %U A154617 16940,18183,19470,20801,22176,23595,25058,26565,28116,29711,31350,33033,34760,36531,38346 %N A154617 Eleven times hexagonal numbers: a(n) = 11*n*(2*n-1). %C A154617 Sequence found by reading the line from 0, in the direction 0, 11, ..., in the square spiral whose vertices are the generalized tridecagonal numbers A195313. - _Omar E. Pol_, Sep 18 2011 %H A154617 Ivan Panchenko, <a href="/A154617/b154617.txt">Table of n, a(n) for n = 0..1000</a> %H A154617 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1). %F A154617 a(n) = 22*n^2 - 11*n = 11*A000384(n). %F A154617 a(n) = a(n-1) + 44*n - 33 (with a(0)=0). - _Vincenzo Librandi_, Dec 15 2010 %F A154617 From _Elmo R. Oliveira_, Dec 15 2024: (Start) %F A154617 G.f.: 11*x*(1 + 3*x)/(1 - x)^3. %F A154617 E.g.f.: 11*x*(1 + 2*x)*exp(x). %F A154617 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n >= 3. (End) %o A154617 (PARI) a(n)=11*n*(2*n-1) \\ _Charles R Greathouse IV_, Jun 17 2017 %Y A154617 Cf. A000384, A002939, A094159, A152745, A153781, A195313. %K A154617 easy,nonn %O A154617 0,2 %A A154617 _Omar E. Pol_, Jan 13 2009