A130227 Smallest integer y satisfying the Pell equation x^2 - n*y^2 = -1 for the values of n given in A031396.

1, 1, 1, 1, 5, 1, 1, 13, 1, 5, 1, 25, 13, 3805, 1, 125, 5, 1, 41, 53, 569, 1, 389, 851525, 73, 1, 61, 5, 149, 1, 9305, 385645, 1, 85, 82596761, 5, 126985, 1, 221, 17, 1, 113, 1517, 4574225, 281, 1, 373, 5, 85, 535979945, 63445, 1, 145, 23725, 7170685, 25, 19805, 1, 55335641, 13

Offset

1,5

Links

Ray Chandler, Table of n, a(n) for n = 1..10000

Prog

(Python)
from itertools import count, islice
from sympy.solvers.diophantine.diophantine import diop_DN
def A130227_gen(startvalue=1): # generator of terms >= startvalue
    for n in count(max(startvalue, 1)):
        if len(d:=[a[1] for a in diop_DN(n, -1)]):
            yield min(d)
A130227_list = list(islice(A130227_gen(), 50)) # Chai Wah Wu, Dec 22 2025

Crossrefs

Cf. A031396, A130226.

Sequence in context: A300035 A391046 A381932 * A114123 A324009 A143007

Adjacent sequences: A130224 A130225 A130226 * A130228 A130229 A130230

Keyword

nonn

Author

Colin Barker, Aug 05 2007

Status

approved