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A351519
a(n) = tau(n) + pi(n) - omega(n).
1
1, 2, 3, 4, 4, 5, 5, 7, 6, 6, 6, 9, 7, 8, 8, 10, 8, 11, 9, 12, 10, 10, 10, 15, 11, 11, 12, 13, 11, 15, 12, 16, 13, 13, 13, 18, 13, 14, 14, 18, 14, 18, 15, 18, 18, 16, 16, 23, 17, 19, 17, 19, 17, 22, 18, 22, 18, 18, 18, 26, 19, 20, 22, 24, 20, 23, 20, 23, 21, 24, 21, 30, 22, 23, 25, 25
OFFSET
1,2
COMMENTS
Number of numbers <= n that are either prime, a divisor of n, or both.
FORMULA
a(n) = A000005(n) + A000720(n) - A001221(n).
MATHEMATICA
Table[DivisorSigma[0, n] + PrimePi[n] - PrimeNu[n], {n, 100}]
CROSSREFS
Cf. A000005 (tau), A000720 (pi), A001221 (omega).
Sequence in context: A358062 A081609 A337020 * A046700 A216411 A110532
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Feb 12 2022
STATUS
approved