Numbers k such that (k^2 - 8)/2 is a square.

Terms

a(0) =4a(1) =20a(2) =116a(3) =676a(4) =3940a(5) =22964a(6) =133844a(7) =780100a(8) =4546756a(9) =26500436a(10) =154455860a(11) =900234724a(12) =5246952484a(13) =30581480180a(14) =178241928596