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A324695 Lexicographically earliest sequence of positive integers whose prime indices are not already in the sequence. 54

%I #7 Mar 11 2019 09:36:49

%S 1,3,7,9,11,13,19,21,27,29,33,37,39,43,47,49,53,57,59,61,63,71,77,79,

%T 81,83,87,89,91,97,99,101,107,111,113,117,121,127,129,131,133,139,141,

%U 143,147,149,151,159,163,169,171,173,177,179,181,183,189,193,197

%N Lexicographically earliest sequence of positive integers whose prime indices are not already in the sequence.

%C A self-describing sequence, similar to A304360.

%C A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.

%e The sequence of terms together with their prime indices begins:

%e 1: {}

%e 3: {2}

%e 7: {4}

%e 9: {2,2}

%e 11: {5}

%e 13: {6}

%e 19: {8}

%e 21: {2,4}

%e 27: {2,2,2}

%e 29: {10}

%e 33: {2,5}

%e 37: {12}

%e 39: {2,6}

%e 43: {14}

%e 47: {15}

%e 49: {4,4}

%e 53: {16}

%e 57: {2,8}

%e 59: {17}

%e 61: {18}

%e 63: {2,2,4}

%t aQ[n_]:=And@@Cases[If[n==1,{},FactorInteger[n]],{p_,k_}:>!aQ[PrimePi[p]]];

%t Select[Range[100],aQ]

%Y Complement of A324694. Prime indices are A304360.

%Y Cf. A000002, A000720, A001222, A001462, A007097, A055396, A061395, A079000, A079254, A109298, A112798, A276625, A277098.

%Y Cf. A324696, A324697, A324698, A324699, A324700, A324701, A324702, A324703, A324704, A324705.

%K nonn

%O 1,2

%A _Gus Wiseman_, Mar 10 2019

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Last modified May 8 04:56 EDT 2024. Contains 372319 sequences. (Running on oeis4.)