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 A161706 #29 Oct 24 2023 02:15:59
%S A161706 1,2,4,5,10,20,21,-27,-201,-626,-1486,-3035,-5608,-9632,-15637,-24267,
%T A161706 -36291,-52614,-74288,-102523,-138698,-184372,-241295,-311419,-396909,
%U A161706 -500154,-623778,-770651,-943900,-1146920,-1383385,-1657259,-1972807
%N A161706 a(n) = (-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120.
%C A161706 {a(k): 0 <= k < 6} = divisors of 20:
%C A161706 a(n) = A027750(A006218(19) + k + 1), 0 <= k < A000005(20).
%H A161706 G. C. Greubel, <a href="/A161706/b161706.txt">Table of n, a(n) for n = 0..1000</a>
%H A161706 Reinhard Zumkeller, <a href="/A161700/a161700.txt">Enumerations of Divisors</a>
%H A161706 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-15,6,-1).
%F A161706 a(n) = C(n,0) + C(n,1) + C(n,2) - 2*C(n,3) + 7*C(n,4) - 11*C(n,5).
%F A161706 G.f.: (1-4*x+7*x^2-9*x^3+15*x^4-21*x^5)/(1-x)^6. - _Colin Barker_, Apr 25 2012
%e A161706 Differences of divisors of 20 to compute the coefficients of their interpolating polynomial, see formula:
%e A161706 1 2 4 5 10 20
%e A161706 1 2 1 5 10
%e A161706 1 -1 4 5
%e A161706 -2 5 1
%e A161706 7 -4
%e A161706 -11
%p A161706 A161706:=n->(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120: seq(A161706(n), n=0..50); # _Wesley Ivan Hurt_, Jul 16 2017
%t A161706 CoefficientList[Series[(1 - 4*x + 7*x^2 - 9*x^3 + 15*x^4 - 21*x^5)/(1 - x)^6, {x, 0, 50}], x] (* _G. C. Greubel_, Jul 16 2017 *)
%o A161706 (Magma) [(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120: n in [0..50]]; // _Vincenzo Librandi_, Dec 27 2010
%o A161706 (PARI) a(n)=(-11*n^5+145*n^4-635*n^3+1115*n^2-494*n+120)/120 \\ _Charles R Greathouse IV_, Sep 24 2015
%o A161706 (Python)
%o A161706 def A161706(n): return (n*(n*(n*(n*(145 - 11*n) - 635) + 1115) - 494) + 120)//15>>3 # _Chai Wah Wu_, Oct 23 2023
%Y A161706 Cf. A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161702, A161703, A000127, A161704, A161707, A161708, A161710, A080856, A161711, A161712, A161713, A161715, A006261.
%Y A161706 Cf. A005018, A161700, A161856. - _Reinhard Zumkeller_, Jun 21 2009
%K A161706 sign,easy
%O A161706 0,2
%A A161706 _Reinhard Zumkeller_, Jun 17 2009