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

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A141099 Number of unordered pairs of odd nonprime numbers that sum to 2n. 4
 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 2, 0, 2, 3, 0, 2, 3, 1, 2, 3, 3, 2, 4, 2, 3, 5, 1, 4, 6, 1, 5, 5, 3, 4, 7, 3, 4, 7, 4, 4, 9, 4, 5, 8, 4, 7, 9, 5, 6, 8, 6, 7, 10, 6, 6, 13, 5, 7, 13, 5, 10, 11, 8, 8, 11, 9, 10, 14, 9, 9, 16, 7, 12, 15, 8, 12, 15, 9, 10, 17, 14, 11, 16, 12, 12, 19, 11, 13, 19 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,15 COMMENTS See A141100 for pairs of odd composite numbers. We have a(n) > 0 except for the 8 values of 2n given in A046458. LINKS T. D. Noe, Table of n, a(n) for n=1..1000 EXAMPLE a(18)=3 because 36 = 1+35 = 9+27 = 15+21. MATHEMATICA Table[cnt=0; Do[If[ !PrimeQ[i] && !PrimeQ[2n-i], cnt++ ], {i, 1, n, 2}]; cnt, {n, 100}] CROSSREFS Cf. A141095, A141097. Sequence in context: A204329 A111565 A299761 * A127710 A137510 A247303 Adjacent sequences: A141096 A141097 A141098 * A141100 A141101 A141102 KEYWORD nonn AUTHOR T. D. Noe, Jun 02 2008, Jun 05 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.

Last modified December 5 21:40 EST 2022. Contains 358594 sequences. (Running on oeis4.)