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 A033589 #17 Feb 22 2022 03:37:25 %S A033589 -1,6,105,440,1155,2394,4301,7020,10695,15470,21489,28896,37835,48450, %T A033589 60885,75284,91791,110550,131705,155400,181779,210986,243165,278460, %U A033589 317015,358974,404481,453680,506715 %N A033589 a(n) = (2*n-1)*(3*n-1)*(4*n-1). %H A033589 G. C. Greubel, <a href="/A033589/b033589.txt">Table of n, a(n) for n = 0..1000</a> %H A033589 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1). %F A033589 a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - _Harvey P. Dale_, Sep 22 2014 %F A033589 G.f.: (-1 +10*x +75*x^2 +60*x^3)/(1-x)^4. - _R. J. Mathar_, Feb 06 2017 %F A033589 From _G. C. Greubel_, Mar 05 2020: (Start) %F A033589 a(n) = n^3 * Pochhammer(2 - 1/n, 3) = Product_{j=2..4} (j*n-1). %F A033589 E.g.f.: (-1 + 7*x + 46*x^2 + 24*x^3)*exp(x). (End) %F A033589 Sum_{n>=1} 1/a(n) = (sqrt(3)/2-1)*Pi + 8*log(2) - 9*log(3)/2. - _Amiram Eldar_, Feb 22 2022 %p A033589 seq( mul(j*n-1, j=2..4), n=0..30); # _G. C. Greubel_, Mar 05 2020 %t A033589 Table[Times@@(n*Range[2,4]-1),{n,0,30}] (* or *) LinearRecurrence[{4,-6,4,-1},{-1,6,105,440},30] (* _Harvey P. Dale_, Sep 22 2014 *) %o A033589 (PARI) vector(31, n, my(m=n-1); prod(j=2,4, j*m-1) ) \\ _G. C. Greubel_, Mar 05 2020 %o A033589 (Magma) [(2*n-1)*(3*n-1)*(4*n-1): n in [0..30]]; // _G. C. Greubel_, Mar 05 2020 %o A033589 (Sage) [product(j*n-1 for j in (2..4)) for n in (0..30)] # _G. C. Greubel_, Mar 05 2020 %Y A033589 Cf. A060747, A033568, A033590. %K A033589 sign,easy %O A033589 0,2 %A A033589 _N. J. A. Sloane_