[seqfan] Re: [LIKELY_SPAM] Re: a(n)+a(a(n)) is prime

Eric Angelini Eric.Angelini at kntv.be
Sat Apr 11 20:44:01 CEST 2015


Admiration! Lars, many thanks 4 the 2 seq!

Catapulté de mon aPhone

> Le 11 avr. 2015 à 19:36, "Lars Blomberg" <lars.blomberg at visit.se> a écrit :
> 
> Hello,
> 
> I find
> 1, 3, 2, 5, 6, 7, 10, 9, 8, 13, 12, 11, 16, 15, 14, 21, 18, 19, 22, 23, 20, 25, 24, 29, 28, 27, 26, 31, 30, 37, 36, 33, 34, 39, 38, 35, 42, 41, 40, 43, 48, 47, 46, 45, 44, 51, 50, 49, 52, 53, 56, 55, 54, 59, 58, 57, 70, 69, 68, 61, 66, 63, 64, 67, 71, 73, 72, 81, 80, 79, 78, 77, 76, 75, 74, 87, 86, 85, 84, 83, 82, 91, 90, 89, 88, 93, 92, 103, 102, 101, 100, 99, 98, 95, 96, 97, 114, 113, 112, 111, 110, 109, 108, 105, 106, 117, 115, 119, 118, 123, 116, 121, 120, 125, 124, 135, 122, 133, 132, 131, 130, 129, 128, 127, 126, 137, 136, 141, 134, 139, 138, 145, 144, 143, 142, 147, 140, 155, 154, 153, 152, 151, 150, 149, 148, 156, 160, 159, 158, 157, 162, 161, 164, 163, 176, 175, 174, 173, 172, 171, 170, 169, 168, 167, 166, 165, 180, 179, 178, 177, 182, 181, 186, 185, 184, 183, 190, 189, 188, 187, 192, 191, 196, 195, 194, 193, 202, 201, 200, 199, 198, 197, 204, 203, 206, 205, 212, 211, 210, 209, 208, 207, 216, 215, 214, 213, 224, 223, 222, 221, 220, 219, 218, 217, 228, 227, 226, 225, 230, 229
> 
> S[22] seems to be 25 instead of 26. 
> 
> The first few unused values after 10,000 terms are
> 4, 17, 32, 60, 62, 65, 94, 104, 107, 146, 269, 272, 451, 574, 637, 672, 674, 676, 678, 683
> 
> Regards,
> Lars
> 
> -----Ursprungligt meddelande-----
> Från: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] För Eric Angelini
> Skickat: den 11 april 2015 15:40
> Till: Sequence Discussion list
> Ämne: [seqfan] a(n)+a(a(n)) is prime
> 
> 
> Hello SeqFans,
> S is the lexicographically first seq where a(n)+a(a(n)) is prime.
> 
> [This is not http://oeis.org/A083569
> as the integers 4, 17, etc. will never
> appear here].
> 
> S=1,3,2,5,6,7,10,9,8,13,12,11,16,15,14,21,18,19,22,23,20,26,24,...
> 
> Example:
> 1 + (the 1st integer of S) is prime (1+1=2)
> 3 + (the 3rd integer of S) is prime (3+2=5)
> 2 + (the 2nd integer of S) is prime (2+3=5)
> 5 + (the 5th integer of S) is prime (5+6=11)
> 6 + (the 6th integer of S) is prime (6+7=13)
> 7 + (the 7th integer of S) is prime (7+10=17)
> 10 + (the 10th integer of S) is prime (10+13=23)
> 9 + (the 9th integer of S) is prime (9+8=17)
> 8 + (the 8th integer of S) is prime (8+9=17) etc.
> S is always extended with the smallest
> integer not yet in S and not leading
> to a contradiction.
> 
> Best,
> É.
> 
> 
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