

A128687


Smallest odd nonprime such that every subset of a(1), ..., a(n) adds to a nonprime.


3



1, 9, 15, 39, 105, 731, 2805, 59535, 2658795, 78060135, 67554224745
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OFFSET

1,2


COMMENTS

The first 8 terms are from Rivera's puzzle 84.
The sequences is infinite [Chris Nash].  N. J. A. Sloane, Jan 20 2017


LINKS

Table of n, a(n) for n=1..11.
Chris Nash, Proof that A052349, A128687, and A128688 are infinite [Cached copy of proof, from The Prime Puzzles and Problems website]
Carlos Rivera, Puzzle 84


CROSSREFS

Cf. A052349 (no restrictions on even or odd), A128688 (restricted to even numbers).
Sequence in context: A307217 A100556 A057478 * A193579 A274757 A146789
Adjacent sequences: A128684 A128685 A128686 * A128688 A128689 A128690


KEYWORD

hard,nonn


AUTHOR

T. D. Noe, Mar 20 2007


EXTENSIONS

a(11) from Donovan Johnson, Apr 18 2010


STATUS

approved



