A324854 Lexicographically earliest sequence containing 1 and all positive integers > 2 whose prime indices already belong to the sequence.
1, 4, 7, 8, 14, 16, 17, 19, 28, 32, 34, 38, 43, 49, 53, 56, 59, 64, 67, 68, 76, 86, 98, 106, 107, 112, 118, 119, 128, 131, 133, 134, 136, 139, 152, 163, 172, 191, 196, 212, 214, 224, 227, 236, 238, 241, 256, 262, 263, 266, 268, 272, 277, 278, 289, 301, 304
Offset: 1
Keywords
Examples
The sequence of terms together with their prime indices begins:
1: {}
4: {1,1}
7: {4}
8: {1,1,1}
14: {1,4}
16: {1,1,1,1}
17: {7}
19: {8}
28: {1,1,4}
32: {1,1,1,1,1}
34: {1,7}
38: {1,8}
43: {14}
49: {4,4}
53: {16}
56: {1,1,1,4}
59: {17}
64: {1,1,1,1,1,1}
67: {19}
68: {1,1,7}
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
- Gus Wiseman, The rooted trees whose Matula-Goebel numbers are the first 64 terms.
Crossrefs
Programs
-
Maple
S:= {1}: for n from 3 to 400 do if map(numtheory:-pi, numtheory:-factorset(n)) subset S then S:= S union {n} fi od: sort(convert(S,list)); # Robert Israel, Mar 19 2019 -
Mathematica
aQ[n_]:=Switch[n,1,True,2,False,,And@@Cases[FactorInteger[n],{p,k_}:>aQ[PrimePi[p]]]]; Select[Range[100],aQ]
Comments