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A062590
Variation on A029834: a discrete version of the Mangoldt function. If n is prime then floor(log(prime(n))) else 0.
3
0, 1, 1, 0, 2, 0, 2, 0, 0, 0, 3, 0, 3, 0, 0, 0, 4, 0, 4, 0, 0, 0, 4, 0, 0, 0, 0, 0, 4, 0, 4, 0, 0, 0, 0, 0, 5, 0, 0, 0, 5, 0, 5, 0, 0, 0, 5, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 5, 0, 5, 0, 0, 0, 0, 0, 5, 0, 0, 0, 5, 0, 5, 0, 0, 0, 0, 0, 5, 0, 0, 0, 6, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 6, 0, 6, 0, 0
OFFSET
1,5
LINKS
FORMULA
a(n) = delta(tau(n), 2) * floor(log(prime(n))) = A010051(n) * A029835(n), where delta is the Kronecker delta function and tau is the number of divisors function. - Alonso del Arte, Sep 11 2013
EXAMPLE
a(5) = 2 because the fifth prime is 11, the logarithm of which is 2.397895...
a(6) = 0 because 6 is not prime.
a(7) = 2 because the seventh prime is 17, the logarithm of which is 2.833213344...
MATHEMATICA
Table[Boole[PrimeQ[n]] Floor[Log[Prime[n]]], {n, 105}] (* Alonso del Arte, Sep 07 2013 *)
PROG
(PARI) v=[]; for(n=1, 150, v=concat(v, if(isprime(n), floor(log(prime(n))), ))); v
CROSSREFS
Cf. A029834.
Sequence in context: A050948 A282695 A292936 * A139215 A139216 A348692
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 03 2001
STATUS
approved