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 A098615 G.f. A(x) satisfies: A(x*G(x)) = G(x), where G(x) is the g.f. for A098614(n) = Fibonacci(n+1)*Catalan(n). 10
 1, 1, 3, 5, 13, 25, 61, 125, 295, 625, 1447, 3125, 7151, 15625, 35491, 78125, 176597, 390625, 880125, 1953125, 4390901, 9765625, 21920913, 48828125, 109486993, 244140625, 547018941, 1220703125, 2733608905, 6103515625, 13662695645, 30517578125, 68294088535, 152587890625, 341399727335, 762939453125, 1706739347095, 3814697265625, 8532741458075, 19073486328125, 42660172763995, 95367431640625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS G.f. satisfies: A(x) = x/(series reversion of x*G098614(x)), where G098614 is the g.f. for A098614 = {1*1, 1*1, 2*2, 3*5, 5*14, 8*42, 13*132, ...}. Hankel transform is 2^n. Image of F(n+1) under the Riordan array (c(x^2),xc(x^2)), c(x) the g.f. of A000108. The sequence 0,1,1,3,5,... has general term sum{k=0..floor(n/2), (C(n-1,k)-C(n-1,k-1))F(n-2k)}. It is the image of the Fibonacci numbers under the transform of generating functions g(x)-> g(xc(x^2)), c(x) the g.f. of A000108. This sequence has Hankel transform -(-4)^((n-1)/2)(1-(-1)^n)/2. - Paul Barry, Oct 01 2007 The sequence of fractions 1, 1/2, 3/4, 5/8, 13/16, 25/32, ... or a(n)/2^n is the image of F(n+1) under the Chebyshev related (rational) Riordan array c((x/2)^2),(x/2)c((x/2)^2)) where c(x) is the g.f. of A000108. The Hankel transform of this fraction sequence is 1/(2^(n^2)). - Paul Barry, Jun 17 2008 LINKS Paul D. Hanna, Table of n, a(n) for n = 0..300 P. Barry, A. Hennessy, Meixner-Type Results for Riordan Arrays and Associated Integer Sequences, J. Int. Seq. 13 (2010) # 10.9.4, example 30. FORMULA G.f.: (sqrt(1-4*x^2) + x) / (1-5*x^2). G.f. satisfies: A(x) = sqrt(1 + 2*x*A(x) + 5*x^2*A(x)^2). - Paul D. Hanna, Nov 18 2014 a(2*n) = A046748(n); a(2*n+1) = 5^n. a(n) = Sum_{k=0..floor((n+1)/2)} (C(n,k)-C(n,k-1))*F(n-2k+1). - Paul Barry, Oct 01 2007 G.f.: 1/(1-x-2x^2/(1-x^2/(1-x^2/(1-x^2/(1-x^2/(1-.... (continued fraction). - Paul Barry, Feb 09 2009 a(n) = Sum_{k=0..n} binomial((n-1)/2,(n-k)/2)*2^(n-k-1)*((-1)^(n-k)+1). - Vladimir Kruchinin, Apr 16 2011 a(n) is the upper left term in M^n, M = an infinite square production matrix as follows:    1, 1, 1, 0, 0, 0, ...    1, 0, 0, 1, 0, 0, ...    1, 0, 0, 0, 1, 0, ...    0, 1, 0, 0, 0, 1, ...    0, 0, 1, 0, 0, 0, ...    0, 0, 0, 1, 0, 0, ...    0, 0, 0, 0, 1, 0, ...    0, 0, 0, 0, 0, 1, ...    ... - Gary W. Adamson, Sep 22 2011 a(n) = Sum_{k, 0<=k<=floor(n/2)} A054335(n-k,n-2k). - Philippe Deléham, Feb 01 2012 a(n) = Sum_{k, 0<=k<=n} A053121(n,k)*A000045(k+1). - Philippe Deléham, Feb 03 2012 n*a(n) +(n-1)*a(n-1) +3*(-3*n+4)*a(n-2) +3*(-3*n+7)*a(n-3) +20*(n-3)*a(n-4) +20*(n-4)*a(n-5)=0. - R. J. Mathar, Jul 21 2017 PROG (PARI) { a(n) = polcoeff((sqrt(1-4*x^2+x^2*O(x^n))+x)/(1-5*x^2), n) } for(n=0, 50, print1(a(n), ", ")) (Maxima) a(n):=sum(binomial((n-1)/2, (n-k)/2)*2^(n-k-1)*((-1)^(n-k)+1), k, 0, n); /* Vladimir Kruchinin, Apr 16 2011 */ CROSSREFS Cf. A098614, A046748. Sequence in context: A320330 A159290 A110494 * A026720 A026003 A103792 Adjacent sequences:  A098612 A098613 A098614 * A098616 A098617 A098618 KEYWORD nonn AUTHOR Paul D. Hanna, Oct 14 2004 STATUS approved

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Last modified October 22 10:24 EDT 2019. Contains 328317 sequences. (Running on oeis4.)