cp's OEIS Frontend

A244633 a(n) = 26*n^2.

%I A244633 #42 Dec 06 2024 13:13:19
%S A244633 0,26,104,234,416,650,936,1274,1664,2106,2600,3146,3744,4394,5096,
%T A244633 5850,6656,7514,8424,9386,10400,11466,12584,13754,14976,16250,17576,
%U A244633 18954,20384,21866,23400,24986,26624,28314,30056,31850,33696,35594,37544,39546,41600,43706
%N A244633 a(n) = 26*n^2.
%C A244633 Sequence found by reading the line from 0, in the direction 0, 26, ..., in the square spiral whose vertices are the generalized 15-gonal numbers. - _Omar E. Pol_, Jul 03 2014
%C A244633 Norms of purely imaginary numbers in Z[sqrt(-26)]. - _Alonso del Arte_, Dec 25 2014
%H A244633 Vincenzo Librandi, <a href="/A244633/b244633.txt">Table of n, a(n) for n = 0..1000</a>
%H A244633 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A244633 G.f.: 26*x*(1 + x)/(1 - x)^3. [corrected by _Bruno Berselli_, Jul 03 2014]
%F A244633 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
%F A244633 a(n) = 26*A000290(n) = 13*A001105(n) = 2*A152742(n). - _Omar E. Pol_, Jul 03 2014
%F A244633 From _Elmo R. Oliveira_, Dec 02 2024: (Start)
%F A244633 E.g.f.: 26*x*(1 + x)*exp(x).
%F A244633 a(n) = n*A252994(n) = A005843(n)*A008595(n). (End)
%p A244633 A244633:=n->26*n^2: seq(A244633(n), n=0..50); # _Wesley Ivan Hurt_, Jul 04 2014
%t A244633 Table[26 n^2, {n, 0, 40}]
%t A244633 26 Range[0, 50]^2 (* _Wesley Ivan Hurt_, Jul 04 2014 *)
%o A244633 (Magma) [26*n^2: n in [0..40]];
%o A244633 (PARI) a(n)=26*n^2 \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A244633 Cf. similar sequences listed in A244630.
%Y A244633 Cf. A000290, A001105, A005843, A008595, A152742, A252994, A277082.
%K A244633 nonn,easy
%O A244633 0,2
%A A244633 _Vincenzo Librandi_, Jul 03 2014