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A323014
a(1) = 0; a(prime) = 1; otherwise a(n) = 1 + a(A181819(n)).
93
0, 1, 1, 2, 1, 3, 1, 2, 2, 3, 1, 4, 1, 3, 3, 2, 1, 4, 1, 4, 3, 3, 1, 4, 2, 3, 2, 4, 1, 3, 1, 2, 3, 3, 3, 3, 1, 3, 3, 4, 1, 3, 1, 4, 4, 3, 1, 4, 2, 4, 3, 4, 1, 4, 3, 4, 3, 3, 1, 5, 1, 3, 4, 2, 3, 3, 1, 4, 3, 3, 1, 4, 1, 3, 4, 4, 3, 3, 1, 4, 2, 3, 1, 5, 3, 3, 3, 4, 1, 5, 3, 4, 3, 3, 3, 4, 1, 4, 4, 3, 1, 3, 1, 4, 3
OFFSET
1,4
COMMENTS
Except for n = 2, same as A182850. Unlike A182850, the terms of this sequence depend only on the prime signature (A101296, A118914) of the index.
FORMULA
For all n >= 1, a(n) = a(A046523(n)). [See comment] - Antti Karttunen, Jun 10 2022
MATHEMATICA
dep[n_]:=If[n==1, 0, If[PrimeQ[n], 1, 1+dep[Times@@Prime/@Last/@FactorInteger[n]]]];
Array[dep, 100]
PROG
(PARI)
A181819(n) = factorback(apply(e->prime(e), (factor(n)[, 2])));
A323014(n) = if(1==n, 0, if(isprime(n), 1, 1+A323014(A181819(n)))); \\ Antti Karttunen, Jun 10 2022
CROSSREFS
Positions of 1's are the prime numbers A000040.
Positions of 2's are the proper prime powers A246547.
Positions of 3's are A182853.
Row lengths of A323023.
Sequence in context: A305818 A303757 A182850 * A350331 A293227 A291208
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 02 2019
EXTENSIONS
Terms a(88) and beyond from Antti Karttunen, Jun 10 2022
STATUS
approved