A260689 Table read by rows: numbers m such that (2*n-m, 2*n+m) is a prime pair.
1, 1, 3, 5, 3, 7, 1, 5, 7, 3, 9, 3, 13, 1, 5, 11, 13, 3, 9, 17, 9, 15, 19, 5, 7, 13, 17, 19, 3, 15, 21, 9, 15, 25, 1, 7, 11, 13, 17, 23, 9, 15, 21, 27, 29, 3, 27, 5, 7, 17, 23, 25, 31, 9, 15, 21, 33, 35, 3, 21, 27, 33, 1, 5, 11, 19, 25, 29, 31, 37, 3, 15, 27
Offset: 2
Examples
. n | T(n,k) | (2*n-T(n,k), 2*n+T(n,k)) k=1..A069360(n) . ----+-----------------+----------------------------------------------- . 2 | 1 | (3,5) . 3 | 1 | (5,7) . 4 | 3,5 | (5,11) (3,13) . 5 | 3,7 | (7,13) (3,17) . 6 | 1,5,7 | (11,13) (7,17) (5,19) . 7 | 3,9 | (11,17) (5,23) . 8 | 3,13 | (13,19) (3,29) . 9 | 1,5,11,13 | (17,19) (13,23) (7,29) (5,31) . 10 | 3,9,17 | (17,23) (11,29) (3,37) . 11 | 9,15,19 | (13,31) (7,37) (3,41) . 12 | 5,7,13,17,19 | (19,29) (17,31) (11,37) (7,41) (5,43) . 13 | 3,15,21 | (23,29) (11,41) (5,47) . 14 | 9,15,25 | (19,37) (13,43) (3,53) . 15 | 1,7,11,13,17,23 | (29,31) (23,37) (19,41) (17,43) (13,47) (7,53) . 16 | 9,15,21,27,29 | (23,41) (17,47) (11,53) (5,59) (3,61) . 17 | 3,27 | (31,37) (7,61) . 18 | 5,7,17,23,25,31 | (31,41) (29,43) (19,53) (13,59) (11,61) (5,67) . 19 | 9,15,21,33,35 | (29,47) (23,53) (17,59) (5,71) (3,73) . 20 | 3,21,27,33 | (37,43) (19,61) (13,67) (7,73) .
Links
Programs
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Haskell
a260689 n k = a260689_tabf !! (n-2) !! (k-1) a260689_row n = [m | m <- [1, 3 .. 2 * n - 3], a010051' (2*n + m) == 1, a010051' (2*n - m) == 1] a260689_tabf = map a260689_row [2..]
Comments