Expansion of (1-sqrt(1-(2*(1-sqrt(1-4*x^2)))/x))/2.

Terms

a(0) =0a(1) =1a(2) =1a(3) =3a(4) =7a(5) =22a(6) =67a(7) =225a(8) =765a(9) =2704a(10) =9710a(11) =35558a(12) =131859a(13) =494892a(14) =1874901a(15) =7162807a(16) =27558511a(17) =106695148a(18) =415346144a(19) =1624780952a(20) =6383671910a(21) =25179642120a(22) =99670897534a(23) =395810459602