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A124876 Number of prime factors (counted with multiplicity) in factorization of A007408(n). 3
0, 2, 1, 3, 2, 4, 3, 2, 3, 5, 3, 3, 3, 2, 1, 4, 2, 5, 1, 3, 2, 6, 2, 4, 2, 1, 3, 5, 3, 6, 1, 2, 3, 2, 3, 10, 4, 4, 5, 5, 8, 7, 7, 2, 4, 7, 3, 2, 4, 3, 2, 5, 3, 4, 2, 8, 3, 4, 4, 5, 3, 3, 7, 2, 5, 10, 4, 2, 6, 8, 3, 6, 6, 4, 3, 6, 4, 7, 4, 4, 3, 4, 8, 5, 7, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = A001222(A007408(n)). - R. J. Mathar, May 18 2007
EXAMPLE
a(1) = 0 since A007408(1) = 1 contains no prime factor,
a(2) = 2 since A007408(2) = 9 = 3 * 3,
a(3) = 1 since A007408(3) = 251 is prime,
a(6) = 4 since A007408(6) = 7 * 7 * 11 * 53.
MAPLE
seq( add(op(2, j), j=op(2, (ifactors@A007408)(n))), n=1..28 );
A001222 := proc(n) numtheory[bigomega](n) ; end: b := fscanf("b007408.txt", "%d %d") : while b <> [] do printf("%d, ", A001222(op(2, b))) ; b := fscanf("b007408.txt", "%d %d") : od : # R. J. Mathar, May 18 2007
MATHEMATICA
Table[PrimeOmega[Numerator[Sum[1/k^3, {k, 1, n}]]], {n, 1, 50}] (* Amiram Eldar, Feb 09 2020 *)
PrimeOmega[Numerator[Accumulate[1/Range[50]^3]]] (* Harvey P. Dale, Aug 28 2023 *)
CROSSREFS
Sequence in context: A320642 A046823 A224989 * A188901 A171618 A344096
KEYWORD
nonn
AUTHOR
M. F. Hasler, Nov 11 2006
EXTENSIONS
More terms from R. J. Mathar, May 18 2007
More terms from Amiram Eldar, Feb 09 2020
STATUS
approved

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Last modified March 29 08:08 EDT 2024. Contains 371265 sequences. (Running on oeis4.)