A111436 Least multiple of n such that every partial concatenation followed by a 1 is prime.

1, 8, 3, 4, 5, 78, 28, 32, 36, 40, 176, 528, 624, 280, 30, 144, 1088, 432, 1273, 120, 1869, 440, 3427, 1632, 2000, 2080, 1701, 2268, 10179, 480, 5270, 2464, 660, 1632, 4970, 1044, 222, 2242, 351, 3120, 5576, 798, 1032, 5896, 630, 230, 1081, 8064, 9261, 9500

Offset

1,2

Links

Table of n, a(n) for n=1..50.

Example

11, 181, 183, 1834, 183451, etc. are all prime.

Mathematica

s = ""; Do[k = 1; While[ !PrimeQ[ToExpression[s <> ToString[k*n] <> "1"]], k++ ]; Print[k*n]; s = s <> ToString[k*n], {n, 1, 100}] (* Ryan Propper, Sep 21 2005 *)

Crossrefs

Sequence in context: A070597 A222232 A091895 * A388704 A388593 A014549

Adjacent sequences: A111433 A111434 A111435 * A111437 A111438 A111439

Keyword

base,nonn

Author

Amarnath Murthy, Aug 03 2005

Extensions

More terms from Ryan Propper, Sep 21 2005

Status

approved