A074811 Least k such that prime(k) >= k*tau(k*n) where tau = A000005.

1, 1, 1, 181, 1, 1061, 1, 1061, 181, 1061, 1, 40123, 1, 1061, 1061, 6473, 1, 40123, 1, 40123, 1061, 1061, 1, 1617211, 181, 1061, 1061, 40123, 1, 1617211, 1, 40123, 1061, 1061, 1061, 10553429, 1, 1061, 1061, 1617211, 1, 1617211, 1, 40123, 40123, 1061, 1, 69709687

Offset

1,4

Comments

Listed terms are = 1 or are primes.

a(n) = 1 iff n = 1 or n is prime. - Bernard Schott, Apr 10 2020

Links

Table of n, a(n) for n=1..48.

Prog

(PARI) a(n)=if(n<0, 0, my(s=1); while(prime(s)<s*numdiv(s*n), s++); s)
(PARI) a(n)= my(k=1, p=2); while(p<k*numdiv(k*n), k++; p=nextprime(p+1)); k; \\ Michel Marcus, Apr 05 2020

Crossrefs

Cf. A000005.

Sequence in context: A358413 A236235 A225349 * A036200 A357657 A253432

Adjacent sequences: A074808 A074809 A074810 * A074812 A074813 A074814

Keyword

nonn

Author

Benoit Cloitre, Sep 08 2002

Extensions

More terms from Jinyuan Wang, Apr 05 2020

Name corrected by Bernard Schott, Apr 10 2020

Status

approved