Block[{d,s,u,q,p,a,k,n},
Print["D = ",d=24009857226825282345490];
s=18;
u[0]=154951144645;
u[1]=10; 
u[2]=2;
u[3]=12;
u[4]=6;
u[5]=1;
u[6]=3;
u[7]=4;
u[8]=3;
u[9]=12;
(*remaining coefficients are symmetric*)
Do[u[s-i]=u[i],{i,1,s/2-1}];
u[s]=2u[0];
u[s+1]=u[1];
(*define sequences p[i] and q[i] by recurrences*)
q[-1]=0;
q[0]=1;
Do[q[i]=u[i]q[i-1]+q[i-2],{i,1,s}];
p[-1]=1;
p[0]=u[0];
Do[p[i]=u[i]p[i-1]+p[i-2],{i,1,s}];
Print["Continued fraction for D: ",
ContinuedFraction[Sqrt[d]]];
Print["D mod 4 = ",Mod[d,4]];
Print["factorization of D ",
FactorInteger[d]," so D is squarefree"];
(*define norm of alpha_i*)
n[i_]:=p[i]^2-d q[i]^2;
Print["Negative norms of convergents for i = 0, 2, 4, ..., 16: ",
Table[n[i],{i,0,s-2,2}]];
Print["The largest negative norm -N is attained for i = 2 (and, symmetrically, 14) and equals ",
Max[Table[n[i],{i,0,s,2}]]];
"Find all a such that -n[2] divides d-a^2";
Reduce[{d-a^2==-n[2]k},{a,k},Integers];
a=4030160489;
Print["Smallest a is ",a," and the bound from Jang-Kim's conjecture is (D-a^2)/N = ",
-(d-a^2)/n[2]];
(*define norm of alpha_{i,r}*)
n[i_,r_]:=(p[i]+r p[i+1])^2-d (q[i]+r q[i+1])^2;
Print["The list of norms N(alpha_{i,r}) of all indecomposables ",TableForm[Table[n[i,r],{i,-1,s-1,2},{r, 0, u[i+2]}],TableHeadings->{Table[i,{i,-1,s-1,2}], None}]];
Print["Maximal norm of an indecomposable is ",Max[Table[n[i,r],{i,-1,s-1,2},{r, 0, u[i+2]}]],", larger than Jang-Kim's bound."];
]

D = 24009857226825282345490
Continued fraction for D: {154951144645,{10,2,12,6,1,3,4,3,12,3,4,3,1,6,12,2,10,309902289290}}
D mod 4 = 2
factorization of D {{2,1},{5,1},{3623,1},{7219,1},{1355771,1},{67710787,1}} so D is squarefree
Negative norms of convergents for i = 0, 2, 4, ..., 16: {-29570169465,-24548583881,-210253141241,-67609706711,-24559791665,-67609706711,-210253141241,-24548583881,-29570169465}
The largest negative norm -N is attained for i = 2 (and, symmetrically, 14) and equals -24548583881
Smallest a is 4030160489 and the bound from Jang-Kim's conjecture is (D-a^2)/N = 977393040249
The list of norms N(alpha_{i,r}) of all indecomposables 
-1		1	280332119826	501523900721	663575342686	766486445721	810257209826	794887635001	720377721246	586727468561	393936876946	142005946401		
1	142005946401	403980048114	616856982065	780636748254	895319346681	960904777346	977393040249	944784135390	863078062769	732274822386	552374414241	323376838334	45282094665
3	45282094665	75770761854											
5	75770761854	283021152215	355052129154	291863692671	93455842766								
7	93455842766	363613551081	584651676066	756570217721	879369176046	953048551041	977608342706	953048551041	879369176046	756570217721	584651676066	363613551081	93455842766
9	93455842766	291863692671	355052129154	283021152215	75770761854								
11	75770761854	45282094665											
13	45282094665	323376838334	552374414241	732274822386	863078062769	944784135390	977393040249	960904777346	895319346681	780636748254	616856982065	403980048114	142005946401
15	142005946401	393936876946	586727468561	720377721246	794887635001	810257209826	766486445721	663575342686	501523900721	280332119826	1		
17		1	280332119826	501523900721	663575342686	766486445721	810257209826	794887635001	720377721246	586727468561	393936876946	142005946401		

Maximal norm of an indecomposable is 977608342706, larger than Jang-Kim's bound.