A103601 Numbers k such that the string 10k is the decimal expansion of a prime number.

1, 3, 7, 9, 13, 19, 21, 31, 33, 39, 49, 51, 61, 63, 69, 87, 91, 93, 97, 103, 111, 133, 139, 141, 151, 159, 163, 169, 177, 181, 193, 211, 223, 243, 247, 253, 259, 267, 271, 273, 289, 301, 303, 313, 321, 331, 333, 337, 343, 357, 369, 391, 399, 427, 429, 433, 453

Offset

1,2

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

1 is in the sequence because 101 is prime.
33 is in the sequence because 1033 is prime.
141 is in the sequence because 10141 is prime.

Mathematica

A103601=Reap[For[n=1, n<10^3, If[PrimeQ[n+10^Floor[Log[10, 100n]]], Sow[n]]; n+=2]][[2, 1]] [From Zak Seidov, Dec 15 2008]

Prog

(Magma) [ n: n in [1..500] | IsPrime(Seqint(Intseq(n) cat [0, 1])) ];

Crossrefs

Sequence in context: A107771 A364614 A215800 * A291344 A297002 A111250

Adjacent sequences: A103598 A103599 A103600 * A103602 A103603 A103604

Keyword

base,nonn

Author

Parthasarathy Nambi, Mar 23 2005

Extensions

More terms from Zak Seidov, Dec 15 2008

Status

approved