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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A051169 Smallest number m such that 2*m - p is composite for the first n primes p. 3
3, 6, 15, 49, 49, 49, 49, 110, 154, 154, 278, 278, 278, 278, 496, 496, 496, 496, 496, 496, 1321, 1321, 1321, 1321, 1321, 1321, 2686, 2686, 2686, 2686, 2686, 2686, 2686, 3713, 3713, 3713, 3713, 3713, 3713, 21766, 21766, 21766, 21766, 21766, 21766, 21766 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
Computed by Peter G. Anderson at the Rochester Institute of Technology.
LINKS
Paul S. Bruckman and T. D. Noe, Table of n, a(n) for n=1..974
EXAMPLE
a(2) = 6 because 2*6-2 = 10 and 2*6-3 = 9 are composite.
MATHEMATICA
a[n_] := a[n] = Catch[For[m = 2, True, m++, If[And @@ (! PrimeQ[2*m - #] &) /@ Prime /@ Range[n], Throw[m]]]]; Table[ Print[a[n]]; a[n], {n, 1, 46}] (* Jean-François Alcover, Jul 17 2012 *)
Module[{nn=50, prs}, prs=Prime[Range[nn]]; Table[SelectFirst[Range[50000], AllTrue[Table[2#-p, {p, Take[prs, n]}], CompositeQ]&], {n, nn}]] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 18 2015 *)
PROG
(Haskell)
a051169 n = head [m | m <- [2..],
all (== 0) $ map (a010051' . (2*m -)) $ take n a000040_list]
-- Reinhard Zumkeller, Apr 09 2015
CROSSREFS
See A051610 and A116111 for records. Cf. A025017.
Sequence in context: A028401 A005655 A277063 * A051610 A322851 A230950
KEYWORD
nice,nonn
AUTHOR
Paul S. Bruckman (pbruckman(AT)hotmail.com)
EXTENSIONS
More terms from Paul S. Bruckman, Jan 20 2007
Edited by N. J. A. Sloane, Apr 14 2007, May 04 2007, Jun 10 2008
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 March 19 03:33 EDT 2024. Contains 370952 sequences. (Running on oeis4.)