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A255248 Fundamental positive solution y = y2(n) of the second class of the Pell equation x^2 - 2*y^2 = -A001132(n), n>=1 (primes congruent to {1,7} mod 8) 4
4, 7, 6, 10, 9, 8, 16, 11, 10, 15, 19, 14, 13, 22, 17, 16, 14, 24, 19, 28, 16, 27, 22, 31, 21, 26, 20, 19, 24, 29, 37, 21, 20, 32, 36, 31, 25, 30, 23, 22, 43, 29, 34, 28, 38, 42, 25, 45, 49, 29, 40, 35, 28, 27, 34, 39, 52, 43, 42, 28, 36, 46, 41, 35, 33, 32 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the corresponding term x2(n) see A255247(n).

See the comments on A255247.

LINKS

Table of n, a(n) for n=1..66.

FORMULA

A255247(n)^2 - 2*a(n)^2 = -A001132(n), n >= 1, gives the second smallest positive (proper) solution of this (generalized) Pell equation.

a(n) = -(2*A255235(n+1) - 3*A255246(n+1)), n >= 1.

EXAMPLE

See A255247.

a(4) = -(2*1 - 3*4) = 12 - 2 = 10.

n=4: 13^2 - 2*10^2 = 169 - 200 = -31 = -A001132(4).

CROSSREFS

Cf. A001132, A255247, A255235, A255246, A254937, A255234, A254931.

Sequence in context: A293904 A069286 A079354 * A122460 A256659 A063845

Adjacent sequences:  A255245 A255246 A255247 * A255249 A255250 A255251

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Feb 19 2015

EXTENSIONS

More terms from Colin Barker, Feb 26 2015

STATUS

approved

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Last modified October 21 01:14 EDT 2019. Contains 328291 sequences. (Running on oeis4.)