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A085036
a(n) = (5*n+2)*(5*n+7).
0
14, 84, 204, 374, 594, 864, 1184, 1554, 1974, 2444, 2964, 3534, 4154, 4824, 5544, 6314, 7134, 8004, 8924, 9894, 10914, 11984, 13104, 14274, 15494, 16764, 18084, 19454, 20874, 22344, 23864, 25434, 27054, 28724, 30444, 32214, 34034, 35904, 37824, 39794, 41814
OFFSET
0,1
COMMENTS
1 = 2/7 + Sum(n=1,inf.,25/a(n)) = 2/7 + 25/84 + 25/204 + 25/374 + 25/594...+...; with partial sums: 2/7, 7/12, 12/17, 17/22...(5n+2)/(5n+7)...==>1
FORMULA
25n^2 + 45n + 14.
MATHEMATICA
Table[(5n+2)(5n+7), {n, 0, 60}] (* or *) LinearRecurrence[{3, -3, 1}, {14, 84, 204}, 60] (* Harvey P. Dale, Jun 17 2023 *)
PROG
(PARI) a(n)=(5*n+2)*(5*n+7) \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
Sequence in context: A376290 A323415 A166389 * A107935 A008451 A033276
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Jun 19 2003
EXTENSIONS
Corrected by Douglas McNeil and Charles R Greathouse IV, Aug 31 2010
STATUS
approved