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%I #10 Aug 18 2015 00:19:55
%S 1,3,5,21,25,539,975,847,43095,112651,146523,639331,3663075,69321747,
%T 885243125,19340767413,25672050625,381540593511,189973174625,
%U 12778871553,886736325865,1491476865543,69915748770125,305795988649809
%N a(n) = denominator of r(n): r(n) is such that the continued fraction (of rational terms) [r(1);r(2),...,r(n)] = n^2, for every positive integer n.
%F For n >= 4, r(n) = -16*(n-1)*(n-2)/((2n-1)*(2n-5)*r(n-1)).
%e 4^2 = 16 = 1 + 1/(1/3 +1/(-24/5 + 21/20)).
%e 5^2 = 25 = 1 + 1/(1/3 +1/(-24/5 + 1/(20/21 -25/112))).
%p L2cfrac := proc(L,targ) local a,i; a := 1/(targ-op(1,L)) ; for i from 2 to nops(L) do a := 1/(a-op(i,L)) ; od: RETURN(a) ; end: A128561 := proc(nmax) local b,n,bnxt; b := [1] ; for n from 2 to nmax do bnxt := L2cfrac(b,n^2) ; b := [op(b),bnxt] ; od: [seq( denom(b[i]),i=1..nops(b))] ; end: A128561(30) ; # _R. J. Mathar_, Oct 09 2007
%Y Cf. A128560.
%K frac,nonn
%O 1,2
%A _Leroy Quet_, Mar 10 2007
%E More terms from _R. J. Mathar_, Oct 09 2007
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