A277925 - OEIS

%I #23 Jun 02 2022 14:50:00

%S 1,8,9,25,49,72,81,121,169,200,225,289,361,392,441,529,625,648,729,

%T 841,961,968,1089,1225,1352,1369,1521,1681,1800,1849,2025,2209,2312,

%U 2401,2601,2809,2888,3025,3249,3481,3528,3721,3969,4225,4232,4489,4761,5000,5041,5329,5625,5832,5929,6241

%N Odd squares and 8 times odd squares, sorted.

%H Robert Israel, <a href="/A277925/b277925.txt">Table of n, a(n) for n = 1..10000</a>

%F Sum_{n>=1} 1/a(n) = 9*Pi^2/64. - _Amiram Eldar_, Jun 02 2022

%p N:= 10000: # to get all terms <= N

%p sort([seq(k^2, k=1..floor(sqrt(N)),2), seq(8*k^2, k=1..floor(sqrt(N/8)),2)]); # _Robert Israel_, Nov 18 2016

%t max = 6000; Sort[Join[Table[n^2, {n, 1, Floor[Sqrt[max]], 2}], Table[8*n^2, {n, 1, Floor[Sqrt[max/8]], 2}]]] (* _Amiram Eldar_, Jun 02 2022 *)

%Y Cf. A016754.

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_, Nov 04 2016, based on a suggestion from _Benoit Cloitre_.

%E More terms from _Joerg Arndt_, Nov 05 2016