login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

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 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A157890 Number of primes between exponents of successive Mersenne primes. 0
0, 0, 0, 1, 0, 0, 2, 6, 5, 3, 2, 66, 12, 95, 120, 10, 115, 127, 18, 593, 29, 130, 896, 180, 155, 2032, 3759, 2104, 1841, 6960, 41452, 7555, 28715 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

a(6) = 0 since 17 is adjacent to 19 (exponent of 7th Mersenne prime); a(7) = 2 since 23 and 29 are between 19 and 31 (exponent of 8th Mersenne prime); a(8) = 6 since 37, 41, 43, 47, 53 and 59 are between 31 and 61 (exponent of 9th Mersenne prime)

LINKS

Table of n, a(n) for n=1..33.

FORMULA

a(n) = (PrimePi(A000043(n+1))-PrimePi(A000043(n)))-1 = (A000720(A000043(n+1))-A000720(A000043(n)))-1. [From Jonathan Vos Post, Mar 09 2009]

CROSSREFS

Cf. A000040, A000043, A046933

Sequence in context: A336074 A021381 A323501 * A329932 A198821 A171897

Adjacent sequences: A157887 A157888 A157889 * A157891 A157892 A157893

KEYWORD

nonn

AUTHOR

Jani Melik, Mar 08 2009, Mar 10 2009

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 5 01:43 EST 2022. Contains 358572 sequences. (Running on oeis4.)