A073273 a(n) = floor(sqrt(prime(n)*prime(n+2))).

3, 4, 7, 9, 13, 15, 19, 23, 26, 32, 35, 39, 43, 47, 52, 56, 62, 65, 69, 74, 77, 83, 89, 94, 99, 103, 105, 109, 117, 121, 131, 134, 142, 144, 152, 156, 161, 167, 172, 176, 184, 186, 193, 195, 203, 210, 218, 225, 229, 233, 236, 244, 248, 256, 262, 266, 272, 275

Offset: 1

Author

Reinhard Zumkeller, Jul 22 2002

Keywords

• nonn

Comments

A000040(n) < a(n) < A000040(n+2).

Examples

			prime(10)*prime(12) = 29*37 = 1073 = 32*32+49, therefore a(10)=32; A073274(10) = prime(11)-a(10) = 31-32 = -1.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A073271, A073274, A078444.

Programs

Magma

[Floor(Sqrt(NthPrime(n)*NthPrime(n+2))): n in [1..60]]; // Vincenzo Librandi, Dec 12 2015

Mathematica

Table[Floor[Sqrt[Prime[n] Prime[n + 2]]], {n, 60}] (* Vincenzo Librandi, Dec 12 2015 *)

PARI

a(n) = sqrtint(prime(n)*prime(n+2)); \\ Michel Marcus, Dec 12 2015

Formula

a(n) = A098090(A028310(n - 1)) + A089038(n). - Miko Labalan, Dec 12 2015