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A240470 Records of the maximum number of distinct rational solutions to x^2 - Dy^2 = t, 0 < D <= k, 0 < t <= k. 1
1, 1, 2, 3, 4, 6, 9, 12, 14, 16, 19, 24, 25, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Values of k are in A240469.

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

All Diophantine equations x^2 - Dy^2 = t, 0 < D <= 16, 0 < t <= 16, D squarefree, have fewer than 4 distinct solutions; the first with 4 solutions is x^2 - 17y^2 = 16 with the solutions (x,y) = (9/2,1/2), (21,5), (4,0), (13,3), so 4 is in sequence.

PROG

(PARI) { r(l, k)=if(!issquarefree(l)||!polisirreducible(z^2-l), return(0)); v=bnfisintnorm(bnfinit(z^2-l), k); if(!#v, return(0)); s=0; for(k=1, #v, p=v[k]; a=polcoeff(p, 0); b=polcoeff(p, 1); f=1; for(l=k+1, #v, p=v[l]; aa=polcoeff(p, 0); bb=polcoeff(p, 1); if(abs(a)==abs(aa)&&abs(b)==abs(bb), f=0; break)); s=s+f); s

m=0; n=0; while(1, n=n+1; res=0; for(l=1, n, rr=r(l, n); if(rr>res, res=rr)); for(k=1, n-1, rr=r(n, k); if(rr>res, res=rr)); if(res>m, m=res; print(res, ", "))) }

CROSSREFS

Sequence in context: A018471 A240307 A128166 * A112249 A204502 A062437

Adjacent sequences:  A240467 A240468 A240469 * A240471 A240472 A240473

KEYWORD

nonn,more

AUTHOR

Ralf Stephan, Apr 06 2014

STATUS

approved

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Last modified September 29 16:13 EDT 2020. Contains 337432 sequences. (Running on oeis4.)