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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 15 16:02 EDT 2020. Contains 336505 sequences. (Running on oeis4.)