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A023038 a(n) = 12a(n-1) - a(n-2). +0
10
1, 6, 71, 846, 10081, 120126, 1431431, 17057046, 203253121, 2421980406, 28860511751, 343904160606, 4097989415521, 48831968825646, 581885636492231, 6933795669081126, 82623662392481281, 984550153040694246 (list; graph; listen)
OFFSET

0,2

COMMENT

Chebyshev's polynomials T(n,x) evaluated at x=6.

a(n+1) give all (nontrivial, integer) solutions of Pell equation a(n+1)^2 - 35*b(n)^2 = +1 with b(n)=A004191(n), n>=0.

a(35+70k)-1 and a(35+70k)+1 are consecutive odd powerful numbers. The first pair is 23101441813552306872262673994181386126+-1. See A076445. - T. D. Noe (noe(AT)sspectra.com), May 04 2006

LINKS

Index entries for sequences related to linear recurrences with constant coefficients

Tanya Khovanova, Recursive Sequences

Index entries for sequences related to Chebyshev polynomials.

FORMULA

a(n) = T(n, 6) = (S(n, 12)-S(n-2, 12))/2 with S(n, x) := U(n, x/2) and T(n), resp. U(n, x), are Chebyshev's polynomials of the first, resp. second, kind. See A053120 and A049310. S(-2, x) := -1, S(-1, x) := 0, S(n, 12)=A004191(n).

a(n) = ((6+sqrt(35))^n + (6-sqrt(35))^n)/2.

G.f.: (1-6*x)/(1-12*x+x^2).

a(n)a(n+3) - a(n+1)a(n+2) = 420. - R. Stephan, Jun 06 2005

CROSSREFS

Cf. A087800.

Sequence in context: A050788 A027317 A099339 this_sequence A092660 A092085 A028844

Adjacent sequences: A023035 A023036 A023037 this_sequence A023039 A023040 A023041

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

EXTENSIONS

Chebyshev comments from W. Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de), Nov 08 2002

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Last modified November 24 14:25 EST 2009. Contains 167438 sequences.


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