

A097705


a(n) = 4a(n1) + 17a(n2), a(0)=0, a(1)=1.


2



1, 4, 33, 200, 1361, 8844, 58513, 384400, 2532321, 16664084, 109705793, 722112600, 4753448881, 31289709724, 205967469873, 1355794944800, 8924626767041, 58747021129764, 386706739558753, 2545526317441000
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OFFSET

1,2


COMMENTS

This is one of only two Lucastype sequences whose 8th term is a square.
The other one is A006131.  Michel Marcus, Dec 07 2012


LINKS

Table of n, a(n) for n=1..20.
A. Bremner and N. Tzanakis, Lucas sequences whose 8th term is a square


FORMULA

G.f.: x/(14x17x^2).
a(n)=(1/42)*[2sqrt(21)]^n*sqrt(21)+(1/42)*sqrt(21)*[2+sqrt(21)]^n, with n>=0. [Paolo P. Lava, Oct 02 2008]


MATHEMATICA

Join[{b=1}, a=0; Table[c=4*b+17*a; a=b; b=c, {n, 40}] (* Vladimir Joseph Stephan Orlovsky, Mar 29 2011 *)


PROG

(Maxima)
a[0]:0$
a[1]:1$
a[n]:=4*a[n1] + 17*a[n2]$
A097705(n):=a[n]$
makelist(A097705(n), n, 1, 30); /* Martin Ettl, Nov 03 2012 */


CROSSREFS

Cf. A006131.
Sequence in context: A013192 A273700 A273708 * A131509 A221030 A081007
Adjacent sequences: A097702 A097703 A097704 * A097706 A097707 A097708


KEYWORD

nonn,easy


AUTHOR

Ralf Stephan, Aug 27 2004


STATUS

approved



