A153167 Numbers n such that n+2 is not a Chen prime.

2, 4, 6, 7, 8, 10, 12, 13, 14, 16, 18, 19, 20, 22, 23, 24, 25, 26, 28, 30, 31, 32, 33, 34, 36, 37, 38, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 82, 83, 84, 85, 86, 88, 89, 90

Offset

1,1

Comments

Contains all strictly positive even numbers A005843.

For each odd k>1 we can accumulate the numbers == k^2-2 (mod 2k) in a row, the last entry equal to A073577(k):

7; (k=3)

13, 23; (k=5)

19, 33, 47; (k=7)

25, 43, 61, 79; (k=9)

31, 53, 75, 97, 119; (k=11)

7, 63, 89, 115, 141, 167; (k=13)

43, 73, 103, 133, 163, 193,223; (k=17)

49, 83, 17, 151,185, 219, 253, 287; (k=19)

Each element T of this table has the format T= k^2-2-j*2*k, so T+2 is of the form k*(k-2*j), therefore not prime, and consequently all elements T are in the sequence.

Links

Table of n, a(n) for n=1..71.

Crossrefs

Cf. A109611, A040976, A073577, A067076.

Sequence in context: A024413 A153347 A330945 * A227187 A047237 A285520

Adjacent sequences: A153164 A153165 A153166 * A153168 A153169 A153170

Keyword

nonn

Author

Vincenzo Librandi, Dec 20 2008

Extensions

Edited, 41, 59 (see A102540) etc. inserted by R. J. Mathar, Oct 16 2009

Status

approved