A133326 Numbers n such that 2*n^2 + 41 is a square.

2, 8, 20, 50, 118, 292, 688, 1702, 4010, 9920, 23372, 57818, 136222, 336988, 793960, 1964110, 4627538, 11447672, 26971268, 66721922, 157200070, 388883860, 916229152, 2266581238, 5340174842, 13210603568, 31124819900, 76997040170, 181408744558, 448771637452

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Index entries for linear recurrences with constant coefficients, signature (0, 6, 0, -1).

Formula

The bisections modulo 2 satisfy the same recurrence relation a(n+2)=6*a(n+1)-a(n)

G.f.: 2*x*(x+1)*(x^2+3*x+1)/(x^2+2*x-1)/(x^2-2*x-1). - R. J. Mathar, Nov 14 2007

Mathematica

LinearRecurrence[{0, 6, 0, -1}, {2, 8, 20, 50}, 40] (* T. D. Noe, Sep 03 2012 *)

Crossrefs

Sequence in context: A066857 A146168 A058405 * A285185 A302323 A192698

Adjacent sequences: A133323 A133324 A133325 * A133327 A133328 A133329

Keyword

nonn

Author

Richard Choulet, Oct 18 2007

Extensions

a(14)-a(23) from Donovan Johnson, Nov 15 2009

a(24)-a(30) from Donovan Johnson, Sep 01 2012

Status

approved