A176888 Unsafe primes minus 1.

1, 2, 12, 16, 18, 28, 30, 36, 40, 42, 52, 60, 66, 70, 72, 78, 88, 96, 100, 102, 108, 112, 126, 130, 136, 138, 148, 150, 156, 162, 172, 180, 190, 192, 196, 198, 210, 222, 228, 232, 238, 240, 250, 256, 268, 270, 276, 280, 282, 292, 306, 310, 312, 316, 330, 336

Offset

1,2

Comments

Non-semiprimes k such that k+1 is a prime.

Links

Table of n, a(n) for n=1..56.

Formula

a(n)=A059456(n)-1.

Mathematica

Select[Prime[Range[70]]-1, PrimeOmega[#]!=2&] (* Harvey P. Dale, Jan 14 2015 *)

Crossrefs

Sequence in context: A102975 A120300 A089021 * A114974 A298001 A071566

Adjacent sequences: A176885 A176886 A176887 * A176889 A176890 A176891

Keyword

nonn

Author

Juri-Stepan Gerasimov, Apr 28 2010

Extensions

Entries checked by R. J. Mathar, May 06 2010

Status

approved