A260874 Smallest prime of the form p//r//p//r//p//r// ...., where p = prime(n), r = A004086(p) and // denotes concatenation.

1331133113, 17711771177117711771177117711771177117711771177117711771177117711771177117, 19911991199119, 23322332233223322332233223322332233223322332233223322332233223322332233223322332233223322332233223322332233223322332233223, 2992299229, 31133113311331

Offset

6,1

Links

Felix Fröhlich, Table of n, a(n) for n = 6..100

Prog

(PARI) a(n) = p=prime(n); r=eval(concat(Vecrev(Str(p)))); s=eval(Str(p, r)); i=0; while(!ispseudoprime(s), if(i%2==0, s=eval(Str(s, p)); i++, s=eval(Str(s, r)); i++)); s

Crossrefs

Cf. A067087, A110408.

Sequence in context: A172787 A172849 A213161 * A251358 A346959 A068746

Adjacent sequences: A260871 A260872 A260873 * A260875 A260876 A260877

Keyword

nonn,base

Author

Felix Fröhlich, Aug 02 2015

Status

approved