[seqfan] Re: [a(n)+a(n1)+a(n+2)] is prime BUT [a(n)+a(n+2]) is not

[Lars Blomberg]

Hello,

I get
1, 2, 8, 7, 4, 18, 21, 14, 6, 11, 12, 24, 23, 20, 10, 13, 30, 36, 5, 26, 16, 19, 32, 38, 3, 42, 22, 9, 28, 46, 27, 34, 48, 15, 40, 54, 37, 58, 44, 29, 64, 56, 17, 66, 68, 33, 50, 84, 45, 52, 60, 25, 72, 70, 39, 82, 76, 35, 62, 94, 43, 74, 80, 69, 78, 86, 47, ...

And the sequence extends to 10^5 terms without problem.

/Lars

-----Ursprungligt meddelande-----
Från: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] För Eric Angelini
Skickat: den 29 januari 2016 19:47
Till: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
Ämne: [seqfan] [a(n)+a(n1)+a(n+2)] is prime BUT [a(n)+a(n+2]) is not

Hello SeqFans,
Does this seq S extend smoothly without backtracking?

Start S with a(1)=1 and extend S with the smallest unused integer such that [a(n)+a(n1)+a(n+2)] is prime BUT [a(n)+a(n+2]) is not.

S=1,2,8,7,4,18,21,14,12,11,6,24,29,20,10,13,30,36,5,26,16,19,32,38,3,42,22,...

I guess S is the lexico-first permutation of the integers >0.
Best,
É.


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