OFFSET
1,2
COMMENTS
FORMULA
a(n) = A324701(n) - 1.
EXAMPLE
The sequence of terms together with their prime indices begins:
0
2: {1}
4: {1,1}
5: {3}
8: {1,1,1}
10: {1,3}
11: {5}
13: {6}
16: {1,1,1,1}
20: {1,1,3}
22: {1,5}
23: {9}
25: {3,3}
26: {1,6}
31: {11}
32: {1,1,1,1,1}
37: {12}
40: {1,1,1,3}
43: {14}
44: {1,1,5}
MATHEMATICA
aQ[n_]:=Switch[n, 0, True, 1, False, _, And@@Cases[FactorInteger[n], {p_, k_}:>aQ[PrimePi[p]-1]]];
Select[Range[0, 100], aQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 10 2019
STATUS
approved