|
| |
|
|
A024675
|
|
Average of two consecutive odd primes.
|
|
64
|
|
|
|
4, 6, 9, 12, 15, 18, 21, 26, 30, 34, 39, 42, 45, 50, 56, 60, 64, 69, 72, 76, 81, 86, 93, 99, 102, 105, 108, 111, 120, 129, 134, 138, 144, 150, 154, 160, 165, 170, 176, 180, 186, 192, 195, 198, 205, 217, 225, 228, 231, 236, 240, 246, 254, 260, 266, 270, 274, 279, 282, 288, 300
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Sometimes called interprimes.
Where local maxima of A072681 occur: A072681(a(n))=A074927(n+1). [From Reinhard Zumkeller, Mar 04 2009]
Never prime, for that would contradict the definition. - Jon Perry, Dec 05 2012
A subset of A145025, obtained from that sequence by omitting the primes (which are barycenter of their neighboring primes). - M. F. Hasler, Jun 01 2013
|
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n=1..10000
Eric Weisstein's World of Mathematics, Interprime
|
|
|
FORMULA
|
a(n) = (prime(n+1)+prime(n+2))/2 = A001043(n+1)/2. - Omar E. Pol, Feb 02 2012
Conjecture: a(n) = ceiling(sqrt(prime(n+1)*prime(n+2))). - Thomas Ordowski, Mar 22 2013
A024675 = A145025 \ A006562 (= A145025 \ A000040). - M. F. Hasler, Jun 01 2013
|
|
|
MAPLE
|
seq( ( (ithprime(x)+ithprime(x+1))/2 ), x=2..40);
|
|
|
MATHEMATICA
|
Plus @@@ Partition[Table[Prime[n], {n, 2, 100}], 2, 1]/2
|
|
|
PROG
|
(PARI) for(X=2, 50, print((prime(X)+prime(X+1))/2)) - Hauke Worpel (thebigh(AT)outgun.com), May 08 2008
|
|
|
CROSSREFS
|
Cf. A072568, A072569. Bisections give A058296, A079424.
Sequence in context: A171845 A157124 A162735 * A163656 A100915 A144922
Adjacent sequences: A024672 A024673 A024674 * A024676 A024677 A024678
|
|
|
KEYWORD
|
nonn,nice,easy
|
|
|
AUTHOR
|
Clark Kimberling
|
|
|
STATUS
|
approved
|
| |
|
|
