login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A227957 Number of primes that are of the form n - 2^k - k^2. 0
0, 0, 1, 1, 1, 2, 0, 2, 0, 2, 1, 1, 1, 2, 1, 1, 0, 1, 2, 3, 1, 2, 0, 2, 1, 1, 1, 1, 0, 2, 1, 2, 0, 3, 1, 1, 2, 1, 2, 2, 0, 1, 1, 2, 2, 2, 0, 2, 2, 1, 2, 0, 0, 2, 2, 1, 0, 1, 1, 3, 2, 3, 1, 3, 0, 0, 1, 2, 2, 3, 0, 1, 1, 3, 2, 3, 0, 1, 2, 2, 1, 1, 0, 2, 1, 2, 1, 2, 0, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Indices of zeros in the sequence are 1, 2, 7, 9, 17, 23, 29, 33, 41, 47, 52, ...

LINKS

Table of n, a(n) for n=1..90.

PROG

(PARI) a(n)=sum(k=0, log(n)\log(2), isprime(n-2^k-k^2)) \\ Charles R Greathouse IV, Mar 18 2014

CROSSREFS

Sequence in context: A230632 A052511 A054533 * A247977 A143232 A096030

Adjacent sequences:  A227954 A227955 A227956 * A227958 A227959 A227960

KEYWORD

nonn,less

AUTHOR

Irina Gerasimova, Oct 26 2013

EXTENSIONS

Terms corrected by R. J. Mathar, Oct 26 2013

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified September 26 15:27 EDT 2017. Contains 292531 sequences.