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 A111954 a(n) = A000129(n) + (-1)^n. 6
 1, 0, 3, 4, 13, 28, 71, 168, 409, 984, 2379, 5740, 13861, 33460, 80783, 195024, 470833, 1136688, 2744211, 6625108, 15994429, 38613964, 93222359, 225058680, 543339721, 1311738120, 3166815963, 7645370044, 18457556053, 44560482148, 107578520351 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) + a(n+1) = A001333(n+1). Inverse binomial transform of A007070 (with prepended 1). Inverse invert transform of A077995. LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (1, 3, 1). FORMULA a(n) = a(n-1) + 3*a(n-2) + a(n-3), n >= 3; G.f. (x-1)/((x+1)*(x^2+2*x-1)); a(n) = (sqrt(2)/4)*((1 + sqrt(2))^n - (1 - sqrt(2))^n)) + (-1)^n; G.f.: G(0)/(2+2*x), where G(k)= 1 + 1/(1 - (x)*(2*k-1)/((x)*(2*k+1) - 1/G(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Aug 10 2013 MATHEMATICA LinearRecurrence[{1, 3, 1}, {1, 0, 3}, 40] (* Harvey P. Dale, Nov 24 2014 *) PROG Floretion Algebra Multiplication Program, FAMP Code: -4ibasejseq[J*D] with J = - .25'i + .25'j + .5'k - .25i' + .25j' + .5k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and D = + .5'i - .25'j + .25'k + .5i' - .25j' + .25k' - .5'ii' - .25'ij' - .25'ik' - .25'ji' - .25'ki' - .5e CROSSREFS Cf. A000129, A001333, A111955, A111956, A007070, A077995. Sequence in context: A187775 A151521 A142860 * A192872 A036672 A174684 Adjacent sequences:  A111951 A111952 A111953 * A111955 A111956 A111957 KEYWORD easy,nonn AUTHOR Creighton Dement, Aug 23 2005 STATUS approved

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