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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: A109732 A114396 A102032 * A152677 A135374 A253582

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 November 12 22:16 EST 2019. Contains 329079 sequences. (Running on oeis4.)