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 A145910 a(n) = (1 + 3*n)*(4 + 3*n)/2. 3
 2, 14, 35, 65, 104, 152, 209, 275, 350, 434, 527, 629, 740, 860, 989, 1127, 1274, 1430, 1595, 1769, 1952, 2144, 2345, 2555, 2774, 3002, 3239, 3485, 3740, 4004, 4277, 4559, 4850, 5150, 5459, 5777, 6104, 6440, 6785, 7139, 7502, 7874 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 REFERENCES R. C. Alperin, A nonlinear recurrence and its relations to Chebyshev polynomials, Fib. Q., Vol. 58, No. 2 (2020), pp. 140-142. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = a(n-1) + 3*(3n+1) = a(n-1) + A017197(n+1). a(n) = 2 + 9/2*n^2 + 15/2*n. - Paolo P. Lava, Oct 28 2008 G.f.: (-2 - 8*x + x^2)/(x-1)^3. - R. J. Mathar, Jan 06 2011 a(n) = A144449(n)/8. a(n) = 2*a(n-1) - a(n-2) + 9. a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). From Amiram Eldar, Mar 11 2022: (Start) Sum_{n>=0} 1/a(n) = 2/3. Sum_{n>=0} (-1)^n/a(n) = 4*Pi/(9*sqrt(3)) + 4*log(2)/9 - 2/3. (End) MAPLE A145910:=n->(1+3*n)*(4+3*n)/2: seq(A145910(n), n=0..100); # Wesley Ivan Hurt, Jul 25 2017 MATHEMATICA Table[(1+3n)(4+3n)/2, {n, 0, 50}] (* Harvey P. Dale, Feb 23 2011 *) PROG (PARI) a(n)=(1+3*n)*(4+3*n)/2 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A017197, A144449. Sequence in context: A324043 A230894 A291152 * A128126 A134647 A004117 Adjacent sequences:  A145907 A145908 A145909 * A145911 A145912 A145913 KEYWORD nonn,easy AUTHOR Paul Curtz, Oct 24 2008 EXTENSIONS Terms a(11)-a(42) from Vincenzo Librandi, Nov 17 2009 STATUS approved

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Last modified August 12 23:52 EDT 2022. Contains 356077 sequences. (Running on oeis4.)