A179443 Numbers m such that m and 10*m + 1 are both composites.

8, 9, 12, 14, 16, 20, 22, 26, 30, 32, 34, 35, 36, 38, 39, 44, 45, 48, 50, 51, 55, 56, 58, 62, 65, 68, 72, 74, 77, 78, 80, 84, 85, 86, 87, 90, 92, 93, 95, 96, 98, 100, 104, 108, 110, 111, 112, 114, 116, 119, 121, 122, 124, 125, 126, 128, 133, 134, 135, 140, 141

Offset

1,1

Comments

Corresponding values of 10*m + 1 are in A179444.

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Prog

(PARI) is(n)={n>1 && !isprime(n) && !isprime(10*n+1)}
select(is, [1..200]) \\ Andrew Howroyd, Jan 04 2020

Crossrefs

Cf. A179444.

Sequence in context: A199635 A131864 A347392 * A264828 A080756 A304661

Adjacent sequences: A179440 A179441 A179442 * A179444 A179445 A179446

Keyword

nonn

Author

Jaroslav Krizek, Jul 14 2010

Extensions

Terms a(43) and beyond from Andrew Howroyd, Jan 04 2020

Status

approved