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 A072251 (3*a(n)+1)/2^(2*n + 1) = 23-6*n. 0
 15, 45, 117, 213, -171, -4779, -35499, -207531, -1092267, -5417643, -25864875, -120236715, -548055723, -2460658347, -10916375211, -47960468139, -209021741739, -904806443691, -3894103681707, -16675926354603, -71101751929515, -301999193762475, -1278365519227563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Related to the Collatz conjecture. LINKS Index entries for linear recurrences with constant coefficients, signature (9, -24, 16). FORMULA a(n) = ((46-12*n)*4^n-1)/3. - Don Reble, Oct 31 2005 a(0)=15, a(1)=45, a(2)=117, a(n)=9*a(n-1)-24*a(n-2)+16*a(n-3). - Harvey P. Dale, Sep 14 2012 G.f.: ( -15+90*x-72*x^2 ) / ( (x-1)*(-1+4*x)^2 ). - R. J. Mathar, Nov 07 2015 MATHEMATICA Table[((46-12n)4^n-1)/3, {n, 0, 30}] (* or *) LinearRecurrence[{9, -24, 16}, {15, 45, 117}, 40] (* Harvey P. Dale, Sep 14 2012 *) CROSSREFS Sequence in context: A278337 A270563 A126228 * A002756 A039450 A127069 Adjacent sequences:  A072248 A072249 A072250 * A072252 A072253 A072254 KEYWORD sign,easy,less AUTHOR N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002 EXTENSIONS Edited and extended by David Wasserman, Dec 27 2006 Corrected by N. J. A. Sloane, Mar 01 2007 STATUS approved

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Last modified September 25 19:14 EDT 2020. Contains 337344 sequences. (Running on oeis4.)