cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A324696 Lexicographically earliest sequence containing 1 and all numbers divisible by prime(m) for some m not already in the sequence.

Original entry on oeis.org

1, 3, 6, 7, 9, 11, 12, 14, 15, 18, 19, 21, 22, 24, 27, 28, 29, 30, 33, 35, 36, 38, 39, 41, 42, 44, 45, 48, 49, 51, 53, 54, 55, 56, 57, 58, 59, 60, 63, 66, 69, 70, 71, 72, 75, 76, 77, 78, 81, 82, 83, 84, 87, 88, 90, 91, 93, 95, 96, 97, 98, 99, 101, 102, 105
Offset: 1

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Author

Gus Wiseman, Mar 10 2019

Keywords

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.

Examples

			The sequence of terms together with their prime indices begins:
   1: {}
   3: {2}
   6: {1,2}
   7: {4}
   9: {2,2}
  11: {5}
  12: {1,1,2}
  14: {1,4}
  15: {2,3}
  18: {1,2,2}
  19: {8}
  21: {2,4}
  22: {1,5}
  24: {1,1,1,2}
  27: {2,2,2}
  28: {1,1,4}
  29: {10}
  30: {1,2,3}
  33: {2,5}
  35: {3,4}
  36: {1,1,2,2}
		

Crossrefs

Programs

  • Mathematica
    aQ[n_]:=n==1||Or@@Cases[FactorInteger[n],{p_,k_}:>!aQ[PrimePi[p]]];
    Select[Range[100],aQ]