A109615 Primes of the form floor((Pi/2)^k).

2, 3, 23, 37, 1373, 3389, 8363, 115459401415242179, 45851925215547567394556916118490828192232481476091362012033249370219, 1299908856087615767823951491725300134515972513464867209212961415385730635249

Offset: 1

Author

Reinhard Zumkeller, Aug 01 2005

Keywords

• nonn

Comments

The given terms of the sequence correspond to k=2, 3, 7, 8, 16, 18, 20 respectively. There are no other terms for k=21..100000. - Emeric Deutsch, Aug 27 2007

Examples

			A014214(20) = floor((Pi/2)^20) = floor(8363.6825...) = 8363 and 8363 = A000040(1047), therefore 8363 is a term.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..14.

Crossrefs

Intersection of A000040 and A014214.

Cf. A077547.

Programs

Maple

a:=proc(n) if isprime(floor(((1/2)*Pi)^n))=true then floor(((1/2)*Pi)^n) else end if end proc: seq(a(n),n=1..100); # Emeric Deutsch, Aug 27 2007

Mathematica

lst={};Do[If[PrimeQ[p=Floor[(Pi/2)^n]],AppendTo[lst,p]],{n,600}];lst

Extensions

a(8)-a(10) from Vincenzo Librandi, Dec 09 2011