A174261 Either n*3-+1 is prime.

1, 8, 12, 16, 18, 22, 26, 28, 30, 32, 38, 42, 44, 52, 54, 56, 58, 70, 74, 78, 84, 86, 88, 92, 98, 102, 106, 110, 112, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 146, 148, 150, 152, 156, 160, 162, 164, 166, 168, 170, 180, 182, 186, 188, 192, 196, 198, 202, 204

Offset

1,2

Links

Table of n, a(n) for n=1..59.

Example

a(1)=1 because 1*3-1=2=prime and 1*3+1=4=composite; a(2)=8 because 8*3-1=23=prime and 8*3+1=25=composite; a(3)=12 because 12*3-1=37=prime and 12*3+1=39=composite.

Crossrefs

Cf. A016477.

Sequence in context: A282671 A192991 A083348 * A063539 A253296 A081925

Adjacent sequences: A174258 A174259 A174260 * A174262 A174263 A174264

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Mar 14 2010

Status

approved