A221718 Floor(sqrt(3*2^n)).

1, 2, 3, 4, 6, 9, 13, 19, 27, 39, 55, 78, 110, 156, 221, 313, 443, 627, 886, 1254, 1773, 2508, 3547, 5016, 7094, 10033, 14188, 20066, 28377, 40132, 56755, 80264, 113511, 160529, 227023, 321059, 454046, 642119, 908093, 1284238, 1816186, 2568476, 3632373, 5136952, 7264747, 10273904, 14529495, 20547809, 29058990, 41095618, 58117981

Offset: 0

Author

N. J. A. Sloane, Jan 30 2013

Keywords

• nonn

Comments

Theorem 3 of Dubickas implies that infinitely many terms of this sequence are divisible by 2 or 3 (and hence infinitely many composites). - Charles R Greathouse IV, Feb 04 2016

References

• Artūras Dubickas, Prime and composite integers close to powers of a number, Monatsh. Math. 158:3 (2009), pp. 271-284.

Links

• N. J. A. Sloane, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A007283, A114183.

Programs

Mathematica

Floor[Sqrt[3*2^Range[0,50]]] (* Harvey P. Dale, Feb 03 2025 *)

PARI

a(n)=sqrtint(3<Charles R Greathouse IV, Feb 04 2016