Total number of line segments between points visible to each other in a square n X n lattice.

Terms

a(0) =0a(1) =6a(2) =28a(3) =86a(4) =200a(5) =418a(6) =748a(7) =1282a(8) =2040a(9) =3106a(10) =4492a(11) =6394a(12) =8744a(13) =11822a(14) =15556a(15) =20074a(16) =25456a(17) =32086a(18) =39724a(19) =48934a(20) =59456a(21) =71554a(22) =85252a(23) =101250a(24) =119040a(25) =139350a(26) =161932a(27) =187254a(28) =215136a(29) =246690