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A306719 Lexicographically earliest sequence containing 2 and all positive integers n such that the prime indices of n - 1 already belong to the sequence. 1

%I #15 Mar 11 2019 09:36:25

%S 2,4,8,10,20,22,28,30,50,58,64,72,80,82,88,108,114,134,148,172,190,

%T 204,214,230,238,244,262,272,312,322,340,344,360,362,400,410,422,442,

%U 458,498,514,552,554,568,594,610,620,640,688,712,730,750,758,784,792,814

%N Lexicographically earliest sequence containing 2 and all positive integers n such that the prime indices of n - 1 already belong to 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.

%F a(n) = A324699(n) + 1.

%t aQ[n_]:=Switch[n,0,False,2,True,_,And@@Cases[FactorInteger[n-1],{p_,k_}:>aQ[PrimePi[p]]]];

%t Select[Range[0,100],aQ]

%Y Prime indices of A324699.

%Y Cf. A000002, A000720, A001222, A001462, A007097, A055396, A061395, A079000, A079254, A109298, A112798, A276625, A277098, A304360.

%Y Cf. A324694, A324695, A324696, A324697, A324698, A324700, A324701, A324702, A324703, A324704, A324705.

%K nonn

%O 1,1

%A _Gus Wiseman_, Mar 11 2019

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Last modified June 10 10:32 EDT 2024. Contains 373264 sequences. (Running on oeis4.)