

A126243


a(n) = smallest prime number p which is the arithmetic mean of nth prime < p and nth prime > p.


5



5, 11, 11, 41, 29, 37, 53, 67, 131, 71, 97, 139, 127, 727, 193, 157, 191, 211, 191, 359, 307, 521, 349, 577, 571, 353, 307, 487, 347, 541, 571, 487, 541, 409, 947, 593, 563, 569, 787, 547, 587, 983, 587, 569, 587, 1223, 563, 557, 1213, 569, 563, 1381, 1213
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OFFSET

1,1


LINKS

Hans Havermann, Table of n, a(n) for n = 1..10000.
Hans Havermann, Plot of n, a(n) for n = 1..10000


EXAMPLE

5 is the smallest prime p = prime(n) such that p = (prime(n1)+prime(n+1))/2 (5 = (3+7)/2).


MATHEMATICA

f[n_] := Block[{k = n + 1, p}, While[p = (Prime[k  n] + Prime[k + n])/2; p != Prime[k], k++ ]; p]; Table[f[n], {n, 58}] (* Ray Chandler, Dec 27 2006 *)


CROSSREFS

Cf. A006562, A119381, A126238A126243.
Sequence in context: A058197 A289464 A289580 * A095805 A244534 A034596
Adjacent sequences: A126240 A126241 A126242 * A126244 A126245 A126246


KEYWORD

nonn


AUTHOR

Artur Jasinski, Dec 21 2006


EXTENSIONS

Extended by Ray Chandler, Dec 27 2006
Figure and bfile updated by Hans Havermann, Feb 07 2007


STATUS

approved



