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A016982 a(n) = (7*n)^2. 2
0, 49, 196, 441, 784, 1225, 1764, 2401, 3136, 3969, 4900, 5929, 7056, 8281, 9604, 11025, 12544, 14161, 15876, 17689, 19600, 21609, 23716, 25921, 28224, 30625, 33124, 35721, 38416, 41209, 44100, 47089 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

From Amiram Eldar, Jan 25 2021: (Start)

Sum_{n>=1} 1/a(n) = Pi^2/294.

Sum_{n>=1} (-1)^(n+1)/a(n) = Pi^2/588.

Product_{n>=1} (1 + 1/a(n)) = sinh(Pi/7)/(Pi/7).

Product_{n>=1} (1 - 1/a(n)) = sin(Pi/7)/(Pi/7). (End)

PROG

(MAGMA) [(7*n)^2: n in [0..50]]; // Vincenzo Librandi, May 21 2011

(PARI) a(n)=(7*n)^2 \\ Charles R Greathouse IV, Jun 17 2017

CROSSREFS

Sequence in context: A251214 A158638 A198386 * A157919 A297895 A204709

Adjacent sequences:  A016979 A016980 A016981 * A016983 A016984 A016985

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified February 26 11:15 EST 2021. Contains 341631 sequences. (Running on oeis4.)