|
| |
|
|
A078496
|
|
Smallest prime p such that p>n and 2*n-p is also prime.
|
|
9
| |
|
|
5, 7, 7, 11, 11, 11, 13, 17, 13, 19, 17, 17, 19, 23, 19, 31, 23, 23, 31, 29, 29, 31, 29, 31, 37, 41, 31, 43, 41, 37, 37, 41, 41, 43, 47, 41, 43, 53, 43, 67, 47, 47, 61, 53, 53, 61, 53, 59, 61, 59, 61, 67, 59, 61, 73, 71, 61, 79, 71, 67, 67, 71, 71, 73, 83, 71, 73, 83, 73, 79
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 4,1
|
|
|
COMMENTS
| Suggested by Goldbach Conjecture.
Values of q from A143697. This follows from the factorization n^2-k^2 = (n-k)(n+k).
|
|
|
LINKS
| P. CAMI, Table of n, a(n) for n = 4..60000
|
|
|
FORMULA
| n>3 integer; a(n)=min{p: p>n; p, 2*n-p are primes}
|
|
|
EXAMPLE
| a(11)=17
|
|
|
MATHEMATICA
| Table[p=n+1; q=2n-p; While[q>0&&!(PrimeQ[p]&&PrimeQ[q]), p++; q-- ]; p, {n, 4, 100}]
|
|
|
CROSSREFS
| Cf. A143697, A078587.
a(n) = 2n - A078587(n)
Cf. A082467
Sequence in context: A201459 A053672 A087525 * A114521 A159482 A033932
Adjacent sequences: A078493 A078494 A078495 * A078497 A078498 A078499
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Serhat Sevki Dincer (sevki(AT)ug.bilkent.edu.tr), Nov 26 2002
|
|
|
EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com), Jan 24 2009 at the suggestion of R. J. Mathar and T. D. Noe.
|
| |
|
|
