A192226 Numbers n such that all integers in the interval (n-2*sqrt(sqrt(n)), n] are composite.

1, 28, 36, 96, 120, 121, 122, 123, 124, 125, 126, 146, 147, 148, 189, 190, 207, 208, 209, 210, 219, 220, 221, 222, 249, 250, 292, 302, 303, 304, 305, 306, 326, 327, 328, 329, 330, 346, 477, 478, 519, 520, 533, 534, 535, 536, 537, 538, 539, 540, 630, 672

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 26 2011

Keywords

• nonn

Comments

a(14432) = 191913030 is probably the last term. Any further terms must be greater than 1.5 * 10^18. - Charles R Greathouse IV, Jun 30 2011

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..14432

Crossrefs

Cf. A188817, A189025, A008995.

Programs

Mathematica

Select[Range[700],NextPrime[#-2Sqrt[Sqrt[#]]]>#&] (* Harvey P. Dale, Jul 27 2011 *)

PARI

is(n)=for(k=0,sqrtnint(16*n-1,4),if(isprime(n-k), return(0))); 1 \\ Charles R Greathouse IV, Aug 26 2015

Extensions

a(12)-a(13) added, a(53)-a(56) corrected by Charles R Greathouse IV, Jun 30 2011