A050269 Smallest value a for Diophantine 1-doubles (a,b) ordered by smallest b.

1, 2, 3, 4, 5, 1, 3, 6, 7, 8, 9, 2, 4, 10, 11, 12, 1, 8, 13, 3, 5, 14, 15, 16, 17, 4, 6, 18, 3, 8, 19, 20, 21, 1, 2, 5, 7, 12, 15, 22, 23, 24, 25, 6, 8, 26, 27, 4, 12, 28, 29, 7, 9, 30, 3, 16, 31, 32, 1, 24, 33, 8, 10, 34, 35, 36, 5, 16, 37, 2, 3, 9, 11, 21, 24, 38, 39, 4, 20, 40, 41

Offset

1,2

Links

Table of n, a(n) for n=1..81.

P. Gibbs, Diophantine quadruples and Cayley's hyperdeterminant, arXiv:math/0107203 [math.NT], 2001.

Eric Weisstein's World of Mathematics, Diophantus Property.

Mathematica

m = 0; Do[If[IntegerQ[Sqrt[a*b + 1]], an[m++] = a], {b, 2, 43}, {a, 1, b}]; Array[an, 81, 0] (* Jean-François Alcover, Feb 04 2019 *)

Prog

(PARI) an=vector(81); m=0; for(b=2, 43, for(a=1, b, if(issquare(a*b+1), an[ m++ ]=a))); an

Crossrefs

Cf. A050270.

Sequence in context: A327463 A279478 A355008 * A097151 A306620 A071500

Adjacent sequences: A050266 A050267 A050268 * A050270 A050271 A050272

Keyword

nonn

Author

Eric W. Weisstein

Status

approved