[seqfan] Re: Four consecutive integers sum up to a prime

franktaw at netscape.net franktaw at netscape.net
Thu Jan 7 18:48:17 CET 2010


Here's 100 terms:

1, 2, 3, 5, 7, 4, 13, 17, 9, 8, 19, 11, 15, 14, 21, 23, 25, 10, 31, 35, 
27, 16, 29, 37, 45, 20, 47, 39, 33, 12, 43, 49, 53, 6, 41, 51, 59, 22, 
61, 55, 73, 34, 65, 57, 67, 38, 71, 63, 69, 24, 77, 81, 75, 18, 83, 87, 
89, 48, 93, 101, 95, 28, 107, 117, 79, 44, 91, 97, 85, 40, 109, 103, 
115, 26, 105, 113, 123, 32, 99, 119, 129, 36, 125, 111, 137, 46, 127, 
121, 139, 52, 131, 135, 143, 30, 141, 147, 145, 54, 133, 155

It does look like a permutation, though the odd numbers come 3 times 
faster than the even ones.

Note also A076990.

Franklin T. Adams-Watters

-----Original Message-----
From: Eric Angelini <Eric.Angelini at kntv.be>

Hello seqFans,
I guess this is a permutation of the natural numbers:

« Smallest positive integer not already in sequence
  with a(n)+a(n+1)+a(n+2)+a(n+3) prime »

S = 1,2,3,5,7,4,13,17,9,8,25,11,15,10,...

Based on:
http://www2.research.att.com/~njas/sequences/A055265




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