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 A072258 a(n) = ((6*n+1)*4^n - 1)/3. 6
 0, 9, 69, 405, 2133, 10581, 50517, 234837, 1070421, 4805973, 21321045, 93672789, 408245589, 1767200085, 7605671253, 32570168661, 138870609237, 589842175317, 2496807654741, 10536986432853 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Related to Collatz function (for n>0). All divisible by 3. LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (9,-24,16). FORMULA G.f.: 3*x*(3-4*x)/((1-x)*(1-4*x)^2). - Bruno Berselli, Dec 16 2011 E.g.f.: ( (1 + 24*x)*exp(4*x) - exp(x) )/3. - G. C. Greubel, Jan 14 2020 MAPLE seq( ((6*n+1)*4^n -1)/3, n=0..40); # G. C. Greubel, Jan 14 2020 MATHEMATICA LinearRecurrence[{9, -24, 16}, {0, 9, 69}, 40] (* G. C. Greubel, Jan 14 2020 *) PROG (PARI) a(n)=((6*n+1)*4^n-1)/3 \\ Charles R Greathouse IV, Oct 07 2015 (Magma) [((6*n+1)*4^n -1)/3: n in [0..40]]; // G. C. Greubel, Jan 14 2020 (Sage) [((6*n+1)*4^n -1)/3 for n in (0..40)] # G. C. Greubel, Jan 14 2020 (GAP) List([0..40], n-> ((6*n+1)*4^n -1)/3); # G. C. Greubel, Jan 14 2020 CROSSREFS Cf. A072257, A072259, A072260. Sequence in context: A193698 A188800 A297393 * A196490 A297593 A198691 Adjacent sequences: A072255 A072256 A072257 * A072259 A072260 A072261 KEYWORD nonn,easy AUTHOR N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002 EXTENSIONS Edited and extended by Henry Bottomley, Aug 06 2002 STATUS approved

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Last modified May 30 12:57 EDT 2023. Contains 363050 sequences. (Running on oeis4.)