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A017390
a(n) = (11*n)^2.
2
0, 121, 484, 1089, 1936, 3025, 4356, 5929, 7744, 9801, 12100, 14641, 17424, 20449, 23716, 27225, 30976, 34969, 39204, 43681, 48400, 53361, 58564, 64009, 69696, 75625, 81796, 88209, 94864, 101761
OFFSET
0,2
FORMULA
From Amiram Eldar, Jan 25 2021: (Start)
Sum_{n>=1} 1/a(n) = Pi^2/726.
Sum_{n>=1} (-1)^(n+1)/a(n) = Pi^2/1452.
Product_{n>=1} (1 + 1/a(n)) = sinh(Pi/11)/(Pi/11).
Product_{n>=1} (1 - 1/a(n)) = sin(Pi/11)/(Pi/11). (End)
G.f.: -((121*x*(1+x))/(-1+x)^3). - Harvey P. Dale, Nov 04 2021
MATHEMATICA
(11 Range[0, 30])^2 (* or *) LinearRecurrence[{3, -3, 1}, {0, 121, 484}, 30] (* Harvey P. Dale, Nov 04 2021 *)
PROG
(Magma) [(11*n)^2: n in [0..40]]; // Vincenzo Librandi, Sep 02 2011
(PARI) a(n)=(11*n)^2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Sequence in context: A036304 A052082 A062555 * A110722 A236181 A077432
KEYWORD
nonn,easy
STATUS
approved