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A164274 (n-th isolated prime) plus (n-th isolated composite). 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 24 00:14 EDT 2021. Contains 345403 sequences. (Running on oeis4.)