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 A072259 ((6n+37)*4^n-1)/3. 4
 12, 57, 261, 1173, 5205, 22869, 99669, 431445, 1856853, 7951701, 33903957, 144004437, 609572181, 2572506453, 10826896725, 45455070549, 190410216789, 796000605525, 3321441375573, 13835521316181, 57541108520277, 238960527103317, 991026480502101 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Related to Collatz function (for n>0). All divisible by 3. LINKS Index entries for linear recurrences with constant coefficients, signature (9,-24,16). FORMULA G.f.: 3*(4-17*x+12*x^2)/((1-x)*(1-4*x)^2). - Bruno Berselli, Dec 16 2011 MATHEMATICA LinearRecurrence[{9, -24, 16}, {12, 57, 261}, 30] (* Harvey P. Dale, Mar 10 2018 *) PROG (PARI) a(n)=((6*n+37)*4^n-1)/3 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A072257, A072258, A072260. Sequence in context: A212065 A121693 A190297 * A272233 A283164 A242983 Adjacent sequences:  A072256 A072257 A072258 * A072260 A072261 A072262 KEYWORD nonn,easy,changed AUTHOR N. Rathankar (rathankar(AT)yahoo.com), Jul 08 2002 EXTENSIONS Edited and extended by Henry Bottomley, Aug 06 2002 More terms from Harvey P. Dale, Mar 10 2018 STATUS approved

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Last modified March 20 23:01 EDT 2018. Contains 300991 sequences. (Running on oeis4.)