A164274 (n-th isolated prime) plus (n-th isolated composite).

6, 29, 49, 65, 83, 109, 139, 155, 191, 205, 251, 277, 311, 349, 361, 395, 413, 481, 505, 545, 599, 677, 695, 739, 815, 877, 917, 949, 979, 1013, 1169, 1189, 1201, 1237, 1265, 1409, 1429, 1451, 1471, 1531, 1595, 1679, 1735, 1757, 1781, 1807, 1919, 1951, 1985, 1997

Offset

1,1

Comments

Isolated composites are composites surrounded by two primes, hence the average of a twin prime pair.

Links

Table of n, a(n) for n=1..50.

Formula

a(n)=A007510(n)+A014574(n). - Index adapted to A014574, Jun 11 2011

Example

a(1)=2+4=6. a(2)=23+6=29.

Mathematica

With[{prs=Prime[Range[300]], nn=50}, tps=Select[Partition[prs, 2, 1], Last[#]-First[#]==2&]; iscos=Mean/@tps; isprs = Complement[prs, Flatten[tps]]; Total/@Thread[{Take[isprs, nn], Take[iscos, nn]}]] (* Harvey P. Dale, Sep 20 2011 *)

Crossrefs

Cf. A007510, A014574.

Sequence in context: A156927 A178366 A175956 * A100874 A047923 A006816

Adjacent sequences: A164271 A164272 A164273 * A164275 A164276 A164277

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Aug 11 2009

Extensions

Edited and corrected by R. J. Mathar, Aug 26 2009

Status

approved