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A276456 Integers n such that the Klein invariant J((-1+sqrt(-n))/2) is a rational number. 0
1, 3, 7, 11, 19, 27, 43, 67, 163 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Probably sequence is finite and complete.

This sequence looks very much like A003173, the Heegner numbers, except for two terms (add 2, remove 27). Is there a proof of this connection? - Luc Rousseau, Nov 30 2017

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

a(1) = 1 because J((-1+sqrt(-1))/2) = 1;

a(2) = 3 because J((-1+sqrt(-3))/2) = 0;

a(3) = 7 because J((-1+sqrt(-7))/2) = -125/64;

a(4) = 11 because J((-1+sqrt(-11))/2) = -512/27;

a(5) = 19 because J((-1+sqrt(-19))/2) = -512;

a(6) = 27 because J((-1+sqrt(-27))/2) = -64000/9;

a(7) = 43 because J((-1+sqrt(-43))/2) = -512000;

a(8) = 67 because J((-1+sqrt(-67))/2) = -85184000;

a(9) = 163 because J((-1+sqrt(-163))/2) = -151931373056000.

MATHEMATICA

Rationalize[N[KleinInvariantJ[(-1+I Sqrt[{1, 3, 7, 11, 19, 27, 43, 67, 163}])/2], 100]]

CROSSREFS

Sequence in context: A181497 A292095 A265323 * A126254 A092102 A158722

Adjacent sequences:  A276453 A276454 A276455 * A276457 A276458 A276459

KEYWORD

nonn

AUTHOR

Artur Jasinski, Sep 03 2016

STATUS

approved

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Last modified May 12 22:49 EDT 2021. Contains 343829 sequences. (Running on oeis4.)