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 A086517 a(1) = 1 and then the smallest odd number not included earlier such that the arithmetic mean of a pair of successive terms is prime. 9
 1, 3, 7, 15, 11, 23, 35, 27, 19, 39, 43, 31, 51, 55, 63, 59, 47, 71, 75, 67, 79, 87, 91, 103, 99, 95, 83, 111, 107, 119, 135, 127, 147, 115, 139, 123, 131, 143, 155, 159, 167, 179, 183, 151, 163, 171, 175, 187, 195, 191, 203, 219, 227, 231, 215, 207, 239, 243, 211 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Second term onwards rearrangement of odd numbers of the type 4n+3. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 PROG (PARI) v=[1]; n=1; while(n<100, s=(n+v[#v])/2; if(type(s)=="t_INT", if(isprime(s)&&!vecsearch(vecsort(v), n), v=concat(v, n); n=0)); n++); v \\ Derek Orr, Jun 16 2015 (Haskell) import Data.List (delete) a086517 n = a086517_list !! (n-1) a086517_list = 1 : f 1 [3, 5 ..] where f x zs = g zs where g (y:ys) = if a010051' ((x + y) `div` 2) == 1 then y : f y (delete y zs) else g ys -- Reinhard Zumkeller, Jun 30 2015 CROSSREFS Cf. A086518. Cf. A259565, A259260, A259429, A259542, A010051, A005408. Sequence in context: A333556 A334782 A102032 * A346296 A332374 A152677 Adjacent sequences: A086514 A086515 A086516 * A086518 A086519 A086520 KEYWORD nonn AUTHOR Amarnath Murthy, Jul 30 2003 EXTENSIONS More terms from David Wasserman, Mar 10 2005 STATUS approved

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Last modified May 29 05:22 EDT 2024. Contains 372921 sequences. (Running on oeis4.)