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A050269 Smallest value a for Diophantine 1-doubles (a,b) ordered by smallest b. 2
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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: A193042 A327463 A279478 * A097151 A306620 A071500

Adjacent sequences:  A050266 A050267 A050268 * A050270 A050271 A050272

KEYWORD

nonn

AUTHOR

Eric W. Weisstein

STATUS

approved

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Last modified March 3 14:58 EST 2021. Contains 341762 sequences. (Running on oeis4.)