A324699 Lexicographically earliest sequence of positive integers whose prime indices minus 1 already belong to the sequence.
1, 3, 7, 9, 19, 21, 27, 29, 49, 57, 63, 71, 79, 81, 87, 107, 113, 133, 147, 171, 189, 203, 213, 229, 237, 243, 261, 271, 311, 321, 339, 343, 359, 361, 399, 409, 421, 441, 457, 497, 513, 551, 553, 567, 593, 609, 619, 639, 687, 711, 729, 749, 757, 783, 791, 813
Offset: 1
Keywords
Examples
The sequence of terms together with their prime indices begins:
1: {}
3: {2}
7: {4}
9: {2,2}
19: {8}
21: {2,4}
27: {2,2,2}
29: {10}
49: {4,4}
57: {2,8}
63: {2,2,4}
71: {20}
79: {22}
81: {2,2,2,2}
87: {2,10}
107: {28}
113: {30}
133: {4,8}
147: {2,4,4}
171: {2,2,8}
189: {2,2,2,4}
Crossrefs
Programs
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Mathematica
aQ[n_]:=Switch[n,0,False,1,True,,And@@Cases[FactorInteger[n],{p,k_}:>aQ[PrimePi[p]-1]]]; Select[Range[100],aQ]
Formula
a(n) = A306719(n) - 1.
Comments