A180450 - OEIS

%I #15 Sep 30 2018 20:20:58

%S 3,5,7,13,19,43,67,71,89,103,107,127,137,163,191,311,317,337,383,397,

%T 431,547,569,577,599,607,653,661,677,701,709,733,757,823,857,977,1021,

%U 1039,1129,1193,1249,1277,1381,1459,1699,1709,1823,1949,2099,2131,2153,2521,2647

%N Primes of the form floor( (n^sqrt(2) + n)/sqrt(2) ).

%C Intersection of A000040 with the sequence 1, 3, 5, 7, 10, 13, 16, 19, 22, 25, 28, 32, 35, ... defined by the floor function.

%H Charles R Greathouse IV, <a href="/A180450/b180450.txt">Table of n, a(n) for n = 1..10000</a>

%p select(isprime,[seq(floor((n^sqrt(2)+n)/sqrt(2)),n=1..350)]); # _Muniru A Asiru_, Sep 29 2018

%t Select[With[{b = Sqrt[2]}, Table[Floor[(n^b + n)/b], {n, 500}]], PrimeQ] (* _G. C. Greubel_, Sep 29 2018 *)

%o (PARI) for(n=1, 148438, if(ispseudoprime(t=floor((n^sqrt(2)+n)/sqrt(2))), print1(t", "))); v \\ _Charles R Greathouse IV_, Feb 18 2011

%K easy,nonn

%O 1,1

%A _William A. Tedeschi_, Sep 07 2010

%E Formula replaced by a comment - _R. J. Mathar_, Sep 09 2010