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 A270307 Expansion of -(4*x^3+8*x^2+4*x+1)/(2*x^4+4*x^3+2*x^2-x-1). 1
 1, 3, 7, 7, 21, 27, 57, 95, 169, 303, 529, 943, 1665, 2943, 5217, 9215, 16321, 28863, 51073, 90367, 159873, 282879, 500481, 885503, 1566721, 2771967, 4904449, 8677375, 15352833, 27163647, 48060417, 85032959, 150448129, 266186751, 470962177 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (-1, 2, 4, 2). FORMULA a(n) = (n+1)*Sum_{k=0..n}(Sum_{l=0..n-k}(binomial(k+1,l)*2^l*(-1)^(n-l-k)*binomial(n-2*l,n-l-k))/(k+1)). MATHEMATICA LinearRecurrence[{-1, 2, 4, 2}, {1, 3, 7, 7}, 50] (* Harvey P. Dale, Apr 11 2017 *) PROG (Maxima) a(n):=(n+1)*sum(sum(binomial(k+1, l)*2^l*(-1)^(n-l-k)*binomial(n-2*l, n-l-k), l, 0, n-k)/(k+1), k, 0, n); CROSSREFS Cf. A001405. Sequence in context: A212286 A157102 A226512 * A261480 A121172 A077629 Adjacent sequences:  A270304 A270305 A270306 * A270308 A270309 A270310 KEYWORD nonn AUTHOR Vladimir Kruchinin, Mar 15 2016 STATUS approved

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Last modified August 23 13:53 EDT 2019. Contains 326227 sequences. (Running on oeis4.)