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.

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

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