a(n) is the sum of squares of the first n positive integers congruent to 2 mod 3.

Terms

a(0) =4a(1) =29a(2) =93a(3) =214a(4) =410a(5) =699a(6) =1099a(7) =1628a(8) =2304a(9) =3145a(10) =4169a(11) =5394a(12) =6838a(13) =8519a(14) =10455a(15) =12664a(16) =15164a(17) =17973a(18) =21109a(19) =24590a(20) =28434a(21) =32659a(22) =37283a(23) =42324a(24) =47800a(25) =53729a(26) =60129a(27) =67018a(28) =74414a(29) =82335