A109615 - OEIS

A109615

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

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

LINKS

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

EXAMPLE

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

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}

CROSSREFS

Cf. A014214, A077547.

Sequence in context: A213971 A024773 A176892 * A101001 A231477 A215325

Adjacent sequences: A109612 A109613 A109614 * A109616 A109617 A109618