1,1

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

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

(PARI) is(n)={n>1 && !isprime(n) && !isprime(10*n+1)}

select(is, [1..200]) \\ Andrew Howroyd, Jan 04 2020

Cf. A179444.

Sequence in context: A168415 A199635 A131864 * A264828 A080756 A304661

Adjacent sequences: A179440 A179441 A179442 * A179444 A179445 A179446

nonn

Jaroslav Krizek, Jul 14 2010

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

approved