The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A066246 0 unless n is a composite number A002808(k) when a(n) = k. 16
 0, 0, 0, 1, 0, 2, 0, 3, 4, 5, 0, 6, 0, 7, 8, 9, 0, 10, 0, 11, 12, 13, 0, 14, 15, 16, 17, 18, 0, 19, 0, 20, 21, 22, 23, 24, 0, 25, 26, 27, 0, 28, 0, 29, 30, 31, 0, 32, 33, 34, 35, 36, 0, 37, 38, 39, 40, 41, 0, 42, 0, 43, 44, 45, 46, 47, 0, 48, 49, 50, 0, 51, 0, 52, 53, 54, 55, 56, 0, 57 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS a(n) = A239968(n) + A010051(n) - 1. - Reinhard Zumkeller, Mar 30 2014 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 MATHEMATICA Module[{k=1}, Table[If[CompositeQ[n], k; k++, 0], {n, 100}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 03 2019 *) PROG (PARI) a(n)=if(isprime(n), 0, max(0, n-primepi(n)-1)) \\ Charles R Greathouse IV, Aug 21 2011 (Haskell) import Data.List (unfoldr, genericIndex) a066246 n = genericIndex a066246_list (n - 1) a066246_list = unfoldr x (1, 1, a002808_list) where    x (i, z, cs'@(c:cs)) | i == c = Just (z, (i + 1, z + 1, cs))                         | i /= c = Just (0, (i + 1, z, cs')) -- Reinhard Zumkeller, Jan 29 2014 CROSSREFS Cf. A049084. Cf. A026233, A026238. Sequence in context: A087819 A290820 A278029 * A198370 A173517 A109921 Adjacent sequences:  A066243 A066244 A066245 * A066247 A066248 A066249 KEYWORD nonn AUTHOR Reinhard Zumkeller, Dec 09 2001 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 August 8 19:29 EDT 2020. Contains 336298 sequences. (Running on oeis4.)