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A176902 Primes p such that p-1 and p+1 are both non-semiprime. 1
2, 17, 19, 29, 31, 41, 43, 53, 67, 71, 79, 89, 97, 101, 103, 109, 113, 127, 131, 137, 139, 149, 151, 163, 173, 181, 191, 197, 199, 211, 223, 229, 233, 239, 241, 251, 257, 269, 271, 281, 283, 293, 307, 311, 317, 331, 337, 349, 353, 367, 373, 379, 389, 401, 409 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Two together with A060254.

LINKS

Table of n, a(n) for n=1..55.

FORMULA

a(n+1)=A060254(n)=A167915(n+1).

EXAMPLE

a(1)=2 because 2-1=1=non-semiprime and 2+1=3=non-semiprime.

CROSSREFS

Sequence in context: A216965 A145100 A145101 * A153261 A080115 A119480

Adjacent sequences:  A176899 A176900 A176901 * A176903 A176904 A176905

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Apr 28 2010

EXTENSIONS

Corrected (233, 239 inserted, 279 and 289 replaced by 379 and 389) by R. J. Mathar, Aug 12 2010

STATUS

approved

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Last modified March 19 23:02 EDT 2019. Contains 321343 sequences. (Running on oeis4.)