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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100802 a(n) = least k >= 0 such that (n+k)/2 is prime. 2
4, 3, 2, 1, 0, 1, 0, 3, 2, 1, 0, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 3, 2, 1, 0, 7, 6, 5, 4, 3, 2, 1, 0, 11, 10, 9, 8, 7, 6, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

If a(n) = k is nonzero then a(n+1) = k-1. a(2p) = 0 for p prime.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

MATHEMATICA

a = {}; Do[k = 0; While[ ! PrimeQ[(n + k)/2], k++ ]; AppendTo[a, k]; , {n, 0, 120}]; a (Chandler)

lk[n_]:=Module[{k=If[EvenQ[n], 0, 1]}, While[!PrimeQ[(n+k)/2], k=k+2]; k]; Array[lk, 120, 0] (* Harvey P. Dale, Nov 25 2016 *)

CROSSREFS

Cf. A100803.

Sequence in context: A067018 A200233 A239475 * A022960 A023446 A258447

Adjacent sequences:  A100799 A100800 A100801 * A100803 A100804 A100805

KEYWORD

nonn,easy

AUTHOR

Amarnath Murthy, Dec 18 2004

EXTENSIONS

Extended by Ray Chandler, Jan 19 2005

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 23 17:41 EDT 2017. Contains 292362 sequences.