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 A081492 #17 Sep 08 2022 08:45:09
%S A081492 1,5,18,54,135,291,560,988,1629,2545,3806,5490,7683,10479,13980,18296,
%T A081492 23545,29853,37354,46190,56511,68475,82248,98004,115925,136201,159030,
%U A081492 184618,213179,244935,280116,318960,361713,408629,459970,516006,577015
%N A081492 Sum of terms in n-th row of A081491.
%C A081492 For odd n a(n) is a multiple of n and a(n)/n is the middle term of the corresponding row.
%H A081492 Harvey P. Dale, <a href="/A081492/b081492.txt">Table of n, a(n) for n = 1..1000</a>
%H A081492 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A081492 a(n) = n*(2*n^3 - 6*n^2 + 13*n - 3)/6.
%F A081492 G.f.: x*(1+x)*(1-x+4*x^2)/(1-x)^5. - _Colin Barker_, Jul 28 2012
%F A081492 E.g.f.: x*(6 +9*x +6*x^2 +2*x^3)/6. - _G. C. Greubel_, Aug 13 2019
%p A081492 seq(n*(2*(n-1)^3+7*n-1)/6, n=1..40); # _G. C. Greubel_, Aug 13 2019
%t A081492 LinearRecurrence[{5,-10,10,-5,1},{1,5,18,54,135},40] (* _Harvey P. Dale_, Jul 01 2018 *)
%o A081492 (PARI) vector(40, n, n*(2*(n-1)^3+7*n-1)/6) \\ _G. C. Greubel_, Aug 13 2019
%o A081492 (Magma) [n*(2*(n-1)^3+7*n-1)/6: n in [1..40]]; // _G. C. Greubel_, Aug 13 2019
%o A081492 (Sage) [n*(2*(n-1)^3+7*n-1)/6 for n in (1..40)] # _G. C. Greubel_, Aug 13 2019
%o A081492 (GAP) List([1..40], n-> n*(2*(n-1)^3+7*n-1)/6); # _G. C. Greubel_, Aug 13 2019
%Y A081492 Cf. A002522, A005408, A081489, A081490, A081491.
%K A081492 nonn,easy
%O A081492 1,2
%A A081492 _Amarnath Murthy_, Mar 25 2003
%E A081492 More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 29 2003.
%E A081492 Formula corrected by _Colin Barker_, Jul 28 2012