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 A257785 Numbers that are Belgian-k for exactly one k. 4

%I

%S 0,47,49,59,65,68,76,78,79,85,87,89,95,96,98,167,177,187,193,194,239,

%T 267,268,269,286,287,293,298,299,338,349,359,367,379,394,397,398,418,

%U 437,438,458,478,479,492,497,498,499,507,528,529,536,547,548,560,568

%N Numbers that are Belgian-k for exactly one k.

%C See A106039 for definition of Belgian-k numbers;

%C A257773(a(n)) = 1;

%C A257778(a(n)) = A257779(a(n)).

%H Reinhard Zumkeller, <a href="/A257785/b257785.txt">Table of n, a(n) for n = 1..10000</a>

%e Let B(n) = A257778(a(n)), the singleton of a(n)-th row in A257770:

%e . n | a(n) | B(n) n | a(n) | B(n) n | a(n) | B(n)

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

%e . 1 | 0 | 0 100 | 763 | 4 1000 | 6702 | 6

%e . 2 | 47 | 3 101 | 766 | 6 1001 | 6706 | 5

%e . 3 | 49 | 6 102 | 768 | 5 1002 | 6709 | 8

%e . 4 | 59 | 3 103 | 769 | 8 1003 | 6719 | 3

%e . 5 | 65 | 4 104 | 779 | 6 1004 | 6725 | 5

%e . 6 | 68 | 6 105 | 781 | 6 1005 | 6728 | 6

%e . 7 | 76 | 4 106 | 785 | 5 1006 | 6730 | 4

%e . 8 | 78 | 3 107 | 787 | 2 1007 | 6736 | 4

%e . 9 | 79 | 8 108 | 788 | 6 1008 | 6742 | 3

%e . 10 | 85 | 7 109 | 789 | 6 1009 | 6747 | 3

%e . 11 | 87 | 4 110 | 790 | 6 1010 | 6748 | 6

%e . 12 | 89 | 4 111 | 793 | 7 1011 | 6752 | 6

%e . 13 | 95 | 2 112 | 794 | 7 1012 | 6753 | 6

%e . 14 | 96 | 6 113 | 795 | 2 1013 | 6755 | 3

%e . 15 | 98 | 4 114 | 796 | 4 1014 | 6756 | 6

%e . 16 | 167 | 6 115 | 797 | 8 1015 | 6758 | 6

%e . 17 | 177 | 4 116 | 798 | 6 1016 | 6766 | 3

%e . 18 | 187 | 2 117 | 799 | 8 1017 | 6768 | 5

%e . 19 | 193 | 1 118 | 805 | 4 1018 | 6770 | 4

%e . 20 | 194 | 2 119 | 807 | 4 1019 | 6772 | 5 .

%o a257785 n = a257785_list !! (n-1)

%o a257785_list = filter ((== 1) . a257773) [0..]

%Y Cf. A257770, A257773, A007088, A257778, A257779.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, May 08 2015

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Last modified April 20 16:04 EDT 2021. Contains 343135 sequences. (Running on oeis4.)