A086531 a(1) = 9; a(n+1) is the least odd composite number not already used such that (a(n+1)+a(n))/2 is prime.

9, 25, 21, 65, 57, 49, 33, 85, 81, 77, 45, 121, 93, 125, 69, 133, 129, 145, 117, 161, 141, 185, 177, 169, 105, 209, 153, 205, 189, 265, 201, 221, 165, 217, 237, 245, 213, 253, 225, 289, 249, 305, 261, 301, 285, 329, 297, 325, 309, 365, 333, 341, 273, 361, 345

Offset

1,1

Comments

Appears to contain all composite numbers of the form 4k+1. - David Wasserman, Mar 15 2005

Links

Table of n, a(n) for n=1..55.

Crossrefs

Cf. A086532.

Sequence in context: A101158 A113496 A343670 * A089091 A282176 A204918

Adjacent sequences: A086528 A086529 A086530 * A086532 A086533 A086534

Keyword

nonn

Author

Amarnath Murthy, Jul 31 2003

Extensions

More terms from David Wasserman, Mar 15 2005

Status

approved