1,1

The primality of the numbers corresponding to the first 4 entries has been certified with Primo.

Table of n, a(n) for n=1..6.

n=15 is in the sequence since the 15-digit number 151515151515151 is prime.

f[n_]:=Block[{d=IntegerDigits@n}, FromDigits@d[[Mod[Range@n - 1, Length@d]+1]]]; Select[Range@1500, PrimeQ@f@# &]

Subsequence of A171491.

Sequence in context: A286391 A034975 A012787 * A030049 A240375 A202809

Adjacent sequences: A216446 A216447 A216448 * A216450 A216451 A216452

nonn,base

Giovanni Resta, Sep 11 2012

approved