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A367170
The number of divisors of the largest unitary divisor of n that is a term of A138302.
4
1, 2, 2, 3, 2, 4, 2, 1, 3, 4, 2, 6, 2, 4, 4, 5, 2, 6, 2, 6, 4, 4, 2, 2, 3, 4, 1, 6, 2, 8, 2, 1, 4, 4, 4, 9, 2, 4, 4, 2, 2, 8, 2, 6, 6, 4, 2, 10, 3, 6, 4, 6, 2, 2, 4, 2, 4, 4, 2, 12, 2, 4, 6, 1, 4, 8, 2, 6, 4, 8, 2, 3, 2, 4, 6, 6, 4, 8, 2, 10, 5, 4, 2, 12, 4, 4
OFFSET
1,2
LINKS
FORMULA
Multiplicative with a(p^e) = A048298(e) + 1.
a(n) = A000005(A367168(n)).
a(n) <= A000005(n), with equality if and only if n is in A138302.
MATHEMATICA
f[p_, e_] := If[e == 2^IntegerExponent[e, 2], e+1, 1]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100]
PROG
(PARI) a(n) = {my(f = factor(n)); prod(i = 1, #f~, if(f[i, 2] == 1 << valuation(f[i, 2], 2), f[i, 2] + 1, 1)); }
CROSSREFS
Similar sequences: A365401, A365402.
Sequence in context: A368543 A359302 A366147 * A369306 A038148 A366742
KEYWORD
nonn,easy,mult
AUTHOR
Amiram Eldar, Nov 07 2023
STATUS
approved