A177044 a(n) = 103*(n-1)-a(n-1) with n>1, a(1)=38.
38, 65, 141, 168, 244, 271, 347, 374, 450, 477, 553, 580, 656, 683, 759, 786, 862, 889, 965, 992, 1068, 1095, 1171, 1198, 1274, 1301, 1377, 1404, 1480, 1507, 1583, 1610, 1686, 1713, 1789, 1816, 1892, 1919, 1995, 2022, 2098, 2125, 2201, 2228, 2304, 2331, 2407, 2434, 2510, 2537
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
Programs
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Magma
[(103+49*(-1)^(n-1)+206*(n-1))/(4): n in [1..50]];
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Mathematica
CoefficientList[Series[(38 + 27 x + 38 x^2)/((1 + x) (x - 1)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Sep 24 2014 *) LinearRecurrence[{1,1,-1},{38,65,141},50] (* Harvey P. Dale, Nov 21 2021 *)
Formula
a(n) = (103+49*(-1)^(n-1)+206*(n-1))/4.
G.f.: x*(38+27*x+38*x^2) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Aug 24 2011
Sum_{n>=1} (-1)^(n+1)/a(n) = tan(27*Pi/206)*Pi/103. - Amiram Eldar, Feb 28 2023
Comments