

A128688


a(1)=1. For n>1, a(n) is the smallest even number such that every subset of a(1), ..., a(n) adds to a nonprime.


3



1, 8, 24, 86, 90, 780, 5940, 52350, 278460, 40768260, 6847205430, 5027286840810
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OFFSET

1,2


COMMENTS

The first 7 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..12.
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), A128687 (restricted to odd numbers).
Sequence in context: A296400 A297808 A097544 * A279162 A217016 A019260
Adjacent sequences: A128685 A128686 A128687 * A128689 A128690 A128691


KEYWORD

hard,nonn


AUTHOR

T. D. Noe, Mar 20 2007


EXTENSIONS

a(11) from Donovan Johnson, Apr 18 2010
a(12) from Donovan Johnson, Jul 06 2010


STATUS

approved



