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A254935 Fundamental positive solution y = y1(n) of the first class of the Pell equation x^2 - 2*y^2 = -A007519(n), n>=1 (primes congruent to 1 mod 8). 6
3, 5, 7, 7, 7, 9, 9, 11, 11, 11, 13, 15, 13, 13, 17, 15, 17, 19, 15, 17, 21, 17, 17, 21, 19, 23, 19, 19, 21, 23, 25, 21, 21, 27, 23, 29, 23, 23, 23, 23 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the corresponding term x1(n) see A254934(n).

See A254934 also for the Nagell reference.

The least positive y solutions (that is the ones of the first class) for the primes +1 and -1 (mod 8) together (including prime 2) are given in A255246.

LINKS

Table of n, a(n) for n=1..40.

FORMULA

A254934(n)^2 - 2*a(n)^2 = -A007519(n) gives the smallest positive (proper) solution of this (generalized) Pell equation.

EXAMPLE

See A254934.

n = 3: 5^2 - 2*7^2 = 25 - 98  = 73.

CROSSREFS

Cf. A007519, A254934, A254936, A254937, A254938, A255232.

Sequence in context: A316189 A297346 A211517 * A104199 A103470 A316852

Adjacent sequences:  A254932 A254933 A254934 * A254936 A254937 A254938

KEYWORD

nonn,look,easy

AUTHOR

Wolfdieter Lang, Feb 18 2015

STATUS

approved

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Last modified December 10 15:09 EST 2019. Contains 329896 sequences. (Running on oeis4.)