This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A102261 a(n) = A002144(n) - A002145(n). 3
 2, 6, 6, 10, 14, 10, 10, 14, 14, 22, 26, 22, 26, 10, 30, 22, 26, 34, 30, 30, 30, 50, 42, 42, 46, 46, 50, 42, 42, 50, 46, 54, 42, 42, 42, 42, 38, 34, 30, 38, 14, 18, 18, 18, 46, 54, 62, 70, 78, 78, 90, 78, 66, 54, 70, 66, 62, 66, 58, 70, 66, 86, 98, 78, 78, 54, 70, 70, 78, 78 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = A108546(2*n+1) - A108546(2*n). LINKS Ivan Neretin, Table of n, a(n) for n = 1..30000 MAPLE A002144 := proc(n) option remember ; if n = 1 then RETURN(5) ; fi; for a from procname(n-1)+2 do if isprime(a) and (a mod 4 = 1 ) then RETURN(a) ; fi; od: end; A002145 := proc(n) option remember ; if n = 1 then RETURN(3) ; fi; for a from procname(n-1)+2 do if isprime(a) and (a mod 4 = 3 ) then RETURN(a) ; fi; od: end; A102261 := proc(n) A002144(n)-A002145(n) ; end: seq(A102261(n), n=1..120) ; # R. J. Mathar, Feb 07 2009 MATHEMATICA nmax = 70; a1 = Select[Range[1, Prime[3*nmax], 4], PrimeQ]; a3 = Select[Range[3, Prime[3*nmax], 4], PrimeQ]; a[n_] := a1[[n]] - a3[[n]]; Table[a[n], {n, 1, nmax}] (* Jean-François Alcover, Dec 17 2013 *) CROSSREFS Sequence in context: A196053 A063210 A114718 * A245486 A147298 A078636 Adjacent sequences:  A102258 A102259 A102260 * A102262 A102263 A102264 KEYWORD sign,look AUTHOR Paul Curtz, Sep 06 2008 EXTENSIONS Edited by N. J. A. Sloane, Sep 06 2008 More terms from R. J. Mathar, Feb 07 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 11 21:00 EST 2019. Contains 329937 sequences. (Running on oeis4.)