The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A086409 a[1]=1; a[n+1]=a[n]-1 if (prime[a[n]]+1)/2 is even, else a[n+1]=a[n]+4. 3
 1, 5, 4, 3, 7, 11, 10, 14, 13, 17, 16, 20, 19, 18, 22, 21, 25, 29, 33, 37, 41, 40, 44, 48, 47, 46, 45, 49, 48, 47, 46, 45, 49, 48, 47, 46, 45, 49, 48, 47, 46, 45, 49, 48, 47, 46, 45, 49, 48, 47, 46 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS There is a cycle starting with a(26)=46: ...46,45,49,48,47,46,... LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE a(3)=4 because a(2)=5, prime[5]=11 (11+1)/2 is even and a(3)=a(2)-1 MATHEMATICA b=1; Prepend[Table[b+=If[EvenQ[(Prime[b]+1)/2], -1, 4], {i, 52}], 1] (*A086409*) NestList[If[EvenQ[(Prime[#]+1)/2], #-1, #+4]&, 1, 50] (* Harvey P. Dale, Mar 05 2020 *) CROSSREFS Cf. A086407, A086408. Sequence in context: A256099 A192918 A092156 * A202412 A194556 A154198 Adjacent sequences: A086406 A086407 A086408 * A086410 A086411 A086412 KEYWORD easy,nonn AUTHOR Zak Seidov, Jul 18 2003 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.

Last modified May 25 14:23 EDT 2024. Contains 372788 sequences. (Running on oeis4.)