login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A073719
a(n) = floor(prime(2^n)/composite(2^n)).
0
0, 0, 0, 1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 8, 9, 10, 11, 12, 12, 13, 14, 15, 15, 16, 17, 18, 18, 19, 20, 20, 21, 22, 23, 23, 24, 25, 26, 26, 27, 28, 28, 29, 30, 31, 31, 32, 33, 33, 34, 35, 36, 36, 37, 38, 38, 39, 40, 41, 41, 42, 43, 43, 44, 45, 46, 46, 47, 48, 48, 49, 50
OFFSET
0,5
FORMULA
a(n) = floor(A000040(A000079(n))/A002818(A000079(n))).
a(n) = floor(A033844(n)/A065856(n)). - Charles R Greathouse IV, Jul 08 2013
MATHEMATICA
c[x_] := FixedPoint[x + PrimePi[#] + 1 &, x]; Table[Floor[Prime[z = 2^n]/c[z]], {n, 40}] (* Jayanta Basu, Jul 08 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Aug 05 2002
EXTENSIONS
Offset changed to 0, a(0) prepended and a(41)-a(70) added by Amiram Eldar, Jun 21 2024
STATUS
approved