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A169643 Numbers n such that neither composite(n)-+1 is composite. 0
1, 2, 6, 10, 19, 28, 42, 51, 75, 79, 104, 114, 138, 148, 152, 178, 187, 212, 221, 247, 278, 338, 348, 372, 423, 465, 490, 504, 525, 539, 669, 679, 683, 709, 729, 848, 858, 873, 883, 909, 961, 1028, 1071, 1080, 1089, 1104, 1202, 1221, 1247, 1251, 1354, 1363 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A066246(A014574(n)). [From Reinhard Zumkeller, Apr 06 2010]

LINKS

Table of n, a(n) for n=1..52.

EXAMPLE

a(1)=1 because composite(1)-1=3=prime and composite(1)+1=5=prime.

CROSSREFS

Cf. A002808, A014574.

Sequence in context: A006553 A054273 A127567 * A005993 A028247 A209535

Adjacent sequences:  A169640 A169641 A169642 * A169644 A169645 A169646

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Apr 04 2010

EXTENSIONS

Corrected by Ray Chandler, Apr 05 2010

STATUS

approved

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Last modified October 26 01:20 EDT 2014. Contains 248566 sequences.