Rationals r(n):=A120784(n)/A120785(n). r(n):=sum(C(k)/16^k,k=0..n) with C(k):=A000108(k) (Catalan numbers). For n=0..30: [1, 17/16, 137/128, 4389/4096, 35119/32768, 561925/524288, 4495433/4194304, 287708141/268435456, 2301665843/2147483648, 36826655919/34359738368, 294613251551/274877906944, 9427624079025/8796093022208, 75420992684203/70368744177664, 1206735883132973/1125899906842624, 9653887065398089/9007199254740992, 1235697544380650237/1152921504606846976, 9885580355062880731/9223372036854775808, 158169285681070914091/147573952589676412928, 1265354285448686722403/1180591620717411303424, 40491337134358858748491/37778931862957161709568, 323930697074872511018033/302231454903657293676544, 5182891153197966292855283/4835703278458516698824704, 41463129225583741778162719/38685626227668133590597632, 2653640270437359645332220841/2475880078570760549798248448, 21229122163498877485133803559/19807040628566084398385987584, 339665954615982040977627457307/316912650057057350374175801344, 2717327636927856330116938792475/2535301200456458802993406410752, 86954484381691402581125429088201/81129638414606681695789005144064, 695635875053531220681971926674403/649037107316853453566312041152512, 11130174000856499531036831103871869/10384593717069655257060992658440192, 89041392006851996248533085487355721/83076749736557242056487941267521536] The values of some partial sums r(n) of the convergent series sum(C(k)/16^k,k=0..infty) are (maple10 10 digits): [1.062500000, 1.071796765, 1.071796770, 1.071796770], k=0,...,3. This series is convergent (due to the quotient criterion). The limit is 4*(2-sqrt(3))= 1.071796769... from the convergent Taylor expansion of sqrt(1+x) for the value x=-1/4 (the radius of convergence is R=1 due to the quotient criterion). The Lagrange remainder sequence for all |x|<1 tends to zero because 0<=|R(n,x)| < (1/2)*(C(n)/4^n) |x|^{n+1}, and (C(k)/4^k)*|x|^(k+1) is a 0-sequence for |x|<1 because the power series having these coefficients has radius of convergence R=1. #########################################################################################################################