# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a171231 Showing 1-1 of 1 %I A171231 #30 Sep 08 2022 08:45:49 %S A171231 2,4,7,14,27,54,107,214,427,854,1707,3414,6827,13654,27307,54614, %T A171231 109227,218454,436907,873814,1747627,3495254,6990507,13981014, %U A171231 27962027,55924054,111848107,223696214,447392427,894784854,1789569707 %N A171231 a(n) = (10*2^n + 3 - (-1)^n)/6. %H A171231 Vincenzo Librandi, Table of n, a(n) for n = 0..1000 %H A171231 Index entries for linear recurrences with constant coefficients, signature (2,1,-2). %F A171231 a(n) = 2*a(n-1) + a(n-2) - 2*a(n-3), n >= 3. %F A171231 a(n+1) - a(n) = A048573(n-1). %F A171231 a(n) = 2*A000975(n+1) - 3*A000975(n-1). %F A171231 a(n) - a(n-2) = 5*2^n. %F A171231 a(n+1) - 2*a(n) = ((-1)^n-1)/2 = -A000035(n). %F A171231 G.f.: ( 2-3*x^2 ) / ( (x-1)*(2*x-1)*(1+x) ). - _R. J. Mathar_, Jul 07 2011 %F A171231 a(n) = ceiling( (5/3)*(2^n) ). - _Wesley Ivan Hurt_, Jun 28 2013 %t A171231 LinearRecurrence[{2,1,-2},{2,4,7},40] (* _Harvey P. Dale_, Feb 11 2015 *) %o A171231 (PARI) a(n)=(10<