A014795 - OEIS

%I #13 Mar 07 2022 03:12:50

%S 1,1225,27225,207025,938961,3136441,8555625,20205025,42837025,

%T 83521321,152300281,262926225,433680625,688275225,1056835081,

%U 1576963521,2294889025,3266694025,4559625625,6253488241,8442118161,11234940025,14758605225,19158712225,24601608801

%N Squares of odd tetrahedral numbers.

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).

%F From _Amiram Eldar_, Mar 07 2022: (Start)

%F a(n) = A015219(n)^2 = ((4*n+1)*(4*n+2)*(4*n+3)/6)^2.

%F Sum_{n>=0} 1/a(n) = 9*Pi*(Pi-3)/4. (End)

%t Table[((4*n+1)*(4*n+2)*(4*n+3)/6)^2, {n, 0, 40}] (* _Amiram Eldar_, Mar 07 2022 *)

%Y Cf. A000292, A015219, A014796.

%K nonn,easy

%O 0,2

%A _Mohammad K. Azarian_

%E More terms from _Erich Friedman_

%E More terms from _Amiram Eldar_, Mar 07 2022