A328671 Numbers whose binary indices are relatively prime and pairwise indivisible.
1, 6, 12, 18, 20, 22, 24, 28, 48, 56, 66, 68, 70, 72, 76, 80, 82, 84, 86, 88, 92, 96, 104, 112, 120, 132, 144, 148, 176, 192, 196, 208, 212, 224, 240, 258, 264, 272, 274, 280, 296, 304, 312, 320, 322, 328, 336, 338, 344, 352, 360, 368, 376, 384, 400, 416, 432
Offset: 1
Keywords
Examples
The sequence of terms together with their binary expansions and binary indices begins: 1: 1 ~ {1} 6: 110 ~ {2,3} 12: 1100 ~ {3,4} 18: 10010 ~ {2,5} 20: 10100 ~ {3,5} 22: 10110 ~ {2,3,5} 24: 11000 ~ {4,5} 28: 11100 ~ {3,4,5} 48: 110000 ~ {5,6} 56: 111000 ~ {4,5,6} 66: 1000010 ~ {2,7} 68: 1000100 ~ {3,7} 70: 1000110 ~ {2,3,7} 72: 1001000 ~ {4,7} 76: 1001100 ~ {3,4,7} 80: 1010000 ~ {5,7} 82: 1010010 ~ {2,5,7} 84: 1010100 ~ {3,5,7} 86: 1010110 ~ {2,3,5,7} 88: 1011000 ~ {4,5,7}
Crossrefs
The version for prime indices (instead of binary indices) is A328677.
Numbers whose binary indices are relatively prime are A291166.
Numbers whose distinct prime indices are pairwise indivisible are A316476.
BII-numbers of antichains are A326704.
Programs
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Mathematica
bpe[n_]:=Join@@Position[Reverse[IntegerDigits[n,2]],1]; stableQ[u_,Q_]:=!Apply[Or,Outer[#1=!=#2&&Q[#1,#2]&,u,u,1],{0,1}]; Select[Range[100],GCD@@bpe[#]==1&&stableQ[bpe[#],Divisible]&]
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