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 A165470 a(0)=1, a(1)=5, a(n)=20*a(n-2)-a(n-1). 1
 1, 5, 15, 85, 215, 1485, 2815, 26885, 29415, 508285, 80015, 10085685, -8485385, 210199085, -379906785, 4583888485, -12182024185, 103859793885, -347500277585, 2424696155285, -9374701706985, 57868624812685 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n)/a(n-1) tends to -5. LINKS FORMULA G.f.: (1+6x)/(1+x-20x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*4^k. a(n) = (10*4^n-(-5)^n)/9. [From Klaus Brockhaus, Sep 25 2009] CROSSREFS Sequence in context: A088935 A183937 A030487 * A165625 A058820 A054363 Adjacent sequences:  A165467 A165468 A165469 * A165471 A165472 A165473 KEYWORD easy,sign AUTHOR Philippe DELEHAM, Sep 20 2009 STATUS approved

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