Numbers k such that 2*k^2 - 1 is a square.

Terms

a(0) =1a(1) =5a(2) =29a(3) =169a(4) =985a(5) =5741a(6) =33461a(7) =195025a(8) =1136689a(9) =6625109a(10) =38613965a(11) =225058681a(12) =1311738121a(13) =7645370045a(14) =44560482149a(15) =259717522849