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A123006 Expansion of x^2/(1 -2*x -121*x^2). 3
0, 1, 2, 125, 492, 16109, 91750, 2132689, 15367128, 288789625, 2437001738, 39817548101, 374512306500, 5566947933221, 56449884952942, 786500469825625, 8403437018957232, 111973430886815089, 1240762741067455250 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
a(n) = 2*a(n-1) + 121*a(n-2).
a(n) = (11*i)^(n-2)*ChebyshevU(n-2, -i/11). - G. C. Greubel, Jul 12 2021
MATHEMATICA
Rest@CoefficientList[Series[x^2/(1 -2*x -121*x^2), {x, 0, 30}], x]
PROG
(Magma) [n le 2 select n-1 else 2*Self(n-1) + 121*Self(n-2): n in [1..30]]; // G. C. Greubel, Jul 12 2021
(Sage) [(11*i)^(n-2)*chebyshev_U(n-2, -i/11) for n in [1..30]] # G. C. Greubel, Jul 12 2021
CROSSREFS
Sequences of the form (m*i)^(n-1)*ChebyshevU(n-1, -i/m): A131577 (m=0), A000129 (m=1), A085449 (m=2), A002534 (m=3), A161007 (m=4), A123004 (m=5), A123005 (m=7), this sequence (m=11).
Sequence in context: A012870 A183720 A042921 * A028481 A049659 A209602
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified March 29 09:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)