In response to a problem posed by Mark Underwood on the "Prime Numbers" Yahoo!Group.

139 and 149 are the smallest consecutive primes with the same terminal digit, so a(2)=139.

Here's a table of the smallest starting points for sequences of increasing length runs of primes with the same terminal digits:

1 | 2 |

2 | 139 |

3 | 1627 |

4 | 18839 |

5 | 123229 |

6 | 776257 |

7 | 3873011 |

8 | 23884639 |

9 | 36539311 |

10 | 196943081 |

11 | 452942827 |

12 | 73712513057 |

13 | 154351758091 / 177746482483 |

14 | 154351758091 |

15 | 4010803176619 |

16 | 6987191424553 (Resta, Nov 2004) |

17 | ??? |

I'd expect these to grow slightly faster than exponentially, so here's a log-plot of those values (doesn't include the 16):

Last modified 2006/05/23, thanks to Jens' eagle eyes.

Another hastily constructed page by Phil Carmody

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