login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A157627 8000n - 6040. 3
1960, 9960, 17960, 25960, 33960, 41960, 49960, 57960, 65960, 73960, 81960, 89960, 97960, 105960, 113960, 121960, 129960, 137960, 145960, 153960, 161960, 169960, 177960, 185960, 193960, 201960, 209960, 217960, 225960, 233960, 241960, 249960 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (80000*n^2-120800*n+45601)^2-(100*n^2-151*n +57)*(8000*n-6040)^2=1 can be written as A157628(n)^2-A157626(n)*a(n)^2=1.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Vincenzo Librandi, X^2-AY^2=1

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

a(n) = 2*a(n-1) - a(n-2).

G.f.: x*(1960+6040*x)/(x-1)^2.

MATHEMATICA

LinearRecurrence[{2, -1}, {1960, 9960}, 40]

PROG

(MAGMA) I:=[1960, 9960]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]];

(PARI) a(n)=8000*n-6040 \\ Charles R Greathouse IV, Dec 27 2011

CROSSREFS

Cf. A157626, A157628.

Sequence in context: A232389 A209946 A200857 * A072598 A159213 A056094

Adjacent sequences:  A157624 A157625 A157626 * A157628 A157629 A157630

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 03 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 21:20 EST 2020. Contains 332195 sequences. (Running on oeis4.)