A192360 Numbers k such that number of primes in the range (k-sqrt(k), k) is equal to number of primes in the range (k, k+sqrt(k)).

1, 4, 5, 6, 9, 12, 15, 17, 18, 19, 22, 25, 30, 35, 42, 51, 53, 54, 59, 60, 61, 64, 67, 68, 69, 72, 76, 77, 78, 81, 82, 83, 88, 89, 92, 104, 105, 106, 120, 132, 133, 134, 135, 136, 143, 144, 149, 150, 151, 152, 153, 154, 157, 161, 163, 164, 165, 166

Offset

1,2

Links

Table of n, a(n) for n=1..58.

Maple

isA192360 := proc(n) plow := floor(n-sqrt(n)) ; phi := ceil(n+sqrt(n)) ; plow := numtheory[pi](n-1)-numtheory[pi](plow) ; phi := numtheory[pi] (phi-1)-numtheory[pi](n) ; plow = phi ; end proc:
for n from 1 to 200 do if isA192360(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Jul 02 2011

Prog

(PARI) isA192360(n)=my(s=sqrtint(n)); 2*primepi(n)-isprime(n)==if(n==s^2, primepi(n-s)+primepi(n+s-1), primepi(n-s-1)+primepi(n+s))

Crossrefs

Cf. A188817, A192221.

Sequence in context: A288695 A182719 A003156 * A115984 A145025 A245236

Adjacent sequences: A192357 A192358 A192359 * A192361 A192362 A192363

Keyword

nonn

Author

Juri-Stepan Gerasimov, Jun 28 2011

Extensions

3 removed by Charles R Greathouse IV, Jun 29 2011

Status

approved