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Distance of positions of first and last occurrence of n in A256918.
5

%I #10 May 03 2015 13:49:04

%S 1,2,6,7,1,3,1,4,10,13,1,4,1,1,1,21,1,24,1,27,1,1,1,10,1,1,26,15,1,11,

%T 1,22,1,1,1,5,1,1,1,19,1,43,1,2,1,1,1,1,1,55,1,2,1,20,1,39,1,1,1,13,1,

%U 1,32,42,1,11,1,2,1,67,1,26

%N Distance of positions of first and last occurrence of n in A256918.

%C a(n) = A257475(n) - A257120(n).

%e Let w(n) = A257218(n),

%e u(n) = A257120(n), xx'(n) = (w(u(n)),w(u(n)+1)),

%e v(n) = A257475(n), yy'(n) = (w(v(n)),w(v(n)+1)):

%e . ----+------+------+------++--------------+------------+---------+

%e . n | a(n) | u(n) | v(n) || xx'(n) | yy'(n) | ... gcd |

%e . ----+------+------+------++--------------+------------+---------+

%e . 1 | 1 | 1 | 2 || (1, 2) | (2, 3) | 1 |

%e . 2 | 2 | 4 | 6 || (6, 4) | (8, 10) | 2 |

%e . 3 | 6 | 3 | 9 || (3, 6) | (15, 9) | 3 |

%e . 4 | 7 | 5 | 12 || (4, 8) | (12, 16) | 4 |

%e . 5 | 1 | 7 | 8 || (10, 5) | (5, 15) | 5 |

%e . 6 | 3 | 11 | 14 || (18, 12) | (24, 30) | 6 |

%e . 7 | 1 | 29 | 30 || (70, 7) | (7, 14) | 7 |

%e . 8 | 4 | 13 | 17 || (16, 24) | (40, 32) | 8 |

%e . 9 | 10 | 10 | 20 || (9, 18) | (36, 27) | 9 |

%e . 10 | 13 | 15 | 28 || (30, 20) | (50, 70) | 10 |

%e . 11 | 1 | 122 | 123 || (660, 11) | (11, 22) | 11 |

%e . 12 | 4 | 19 | 23 || (48, 36) | (72, 60) | 12 |

%e . 13 | 1 | 200 | 201 || (1092, 13) | (13, 26) | 13 |

%e . 14 | 1 | 31 | 32 || (14, 28) | (28, 42) | 14 |

%e . 15 | 1 | 24 | 25 || (60, 45) | (45, 75) | 15 |

%e . 16 | 21 | 18 | 39 || (32, 48) | (112, 64) | 16 |

%e . 17 | 1 | 299 | 300 || (2142, 17) | (17, 34) | 17 |

%e . 18 | 24 | 22 | 46 || (54, 72) | (90, 108) | 18 |

%e . 19 | 1 | 824 | 825 || (10260, 19) | (19, 38) | 19 |

%e . 20 | 27 | 16 | 43 || (20, 40) | (80, 100) | 20 |

%e . 21 | 1 | 33 | 34 || (42, 21) | (21, 63) | 21 |

%e . 22 | 1 | 124 | 125 || (22, 44) | (44, 66) | 22 |

%e . 23 | 1 | 945 | 946 || (12420, 23) | (23, 46) | 23 |

%e . 24 | 10 | 41 | 51 || (96, 120) | (144, 168) | 24 |

%e . 25 | 1 | 26 | 27 || (75, 25) | (25, 50) | 25 | .

%o (Haskell)

%o a257478 n = a257475 n - a257120 n

%Y Cf. A256918, A257120, A257475, A257218.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 25 2015

%E a(37)-a(72) from _Hiroaki Yamanouchi_, May 03 2015