



672, 1358, 2044, 2730, 3416, 4102, 4788, 5474, 6160, 6846, 7532, 8218, 8904, 9590, 10276, 10962, 11648, 12334, 13020, 13706, 14392, 15078, 15764, 16450, 17136, 17822, 18508, 19194, 19880, 20566, 21252, 21938, 22624, 23310, 23996, 24682
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

The identity (4802*n^2196*n+1)^2(49*n^22*n)*(686*n14)^2=1 can be written as A157364(n)^2A157362(n)*a(n)^2=1.


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Vincenzo Librandi, X^2AY^2=1
Index entries for linear recurrences with constant coefficients, signature (2,1).


FORMULA

a(n) = 2*a(n1) a(n2).
G.f.: 14*x*(48+x)/(1x)^2.
E.g.f.: 14*(1  (149*x)*exp(x)).  G. C. Greubel, Feb 02 2018


MATHEMATICA

LinearRecurrence[{2, 1}, {672, 1358}, 50]


PROG

(Magma) I:=[672, 1358]; [n le 2 select I[n] else 2*Self(n1)Self(n2): n in [1..40]];
(PARI) a(n) = 686*n14.


CROSSREFS

Cf. A157362, A157364.
Sequence in context: A053085 A057695 A233315 * A308574 A234732 A057805
Adjacent sequences: A157360 A157361 A157362 * A157364 A157365 A157366


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Feb 28 2009


STATUS

approved



