A324694 - OEIS

A324694

Lexicographically earliest sequence of positive integers divisible by prime(m) for some m not already in the sequence.

2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 17, 18, 20, 22, 23, 24, 25, 26, 28, 30, 31, 32, 34, 35, 36, 38, 40, 41, 42, 44, 45, 46, 48, 50, 51, 52, 54, 55, 56, 58, 60, 62, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 78, 80, 82, 84, 85, 86, 88, 90, 92, 93, 94, 95

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OFFSET

1,1

COMMENTS

A self-describing sequence, similar to A304360.

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.

LINKS

Table of n, a(n) for n=1..66.

EXAMPLE

The sequence of terms together with their prime indices begins:

2: {1}

4: {1,1}

5: {3}

6: {1,2}

8: {1,1,1}

10: {1,3}

12: {1,1,2}

14: {1,4}

15: {2,3}

16: {1,1,1,1}

17: {7}

18: {1,2,2}

20: {1,1,3}

22: {1,5}

23: {9}

24: {1,1,1,2}

25: {3,3}

26: {1,6}

28: {1,1,4}

30: {1,2,3}

MATHEMATICA

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

Select[Range[100], aQ]

CROSSREFS

Complement of A324695.

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

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

Sequence in context: A026441 A047434 A062414 * A249025 A065502 A077255

Adjacent sequences: A324691 A324692 A324693 * A324695 A324696 A324697

KEYWORD

nonn

AUTHOR

Gus Wiseman, Mar 10 2019

STATUS

approved