login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130742 Reciprocal of the base 2 logarithm of the ratio between consecutive primes, rounded down. 0
1, 1, 2, 1, 4, 2, 6, 3, 2, 10, 3, 6, 14, 7, 5, 6, 20, 7, 11, 24, 8, 14, 9, 8, 17, 35, 18, 37, 19, 5, 22, 15, 47, 9, 51, 17, 18, 28, 19, 20, 62, 12, 66, 33, 68, 11, 12, 38, 79, 40, 27, 83, 17, 29, 30, 30, 93, 31, 48, 97, 19, 14, 53, 108, 54, 16, 38, 23, 120, 60, 41, 31, 42, 43, 66, 44, 34 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The power to which you must raise the fraction p(n+1)/p(n) to obtain a result which is greater than 2. It has been proved that lim inf of this sequence is (positive) infinity; eg. the ratio between subsequent primes tends to 1.

LINKS

Table of n, a(n) for n=1..77.

FORMULA

a(n) = floor(1 / log_2 (p(n) / p(n+1)))

EXAMPLE

a(5) = 4 because the sixth prime 11 divided by the fifth prime 13 has base two logarithm 0.241008.. and this lies between 1/4 and 1/5.

MATHEMATICA

f[n_] := Floor[1/Log[2, Prime[n + 1]/Prime[n]]]

CROSSREFS

Cf. A000523, A000040, A074461.

Sequence in context: A109170 A225368 A099311 * A130107 A107130 A194747

Adjacent sequences:  A130739 A130740 A130741 * A130743 A130744 A130745

KEYWORD

easy,nonn

AUTHOR

Jack W Grahl, Jul 07 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 20 04:44 EST 2020. Contains 332063 sequences. (Running on oeis4.)