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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A225518 Number of ways to express 2n+1 as p + 8*q, with p and q primes. 1
 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 2, 2, 1, 1, 2, 1, 1, 1, 2, 2, 3, 0, 1, 3, 1, 2, 3, 2, 3, 1, 2, 3, 2, 1, 2, 3, 1, 1, 3, 2, 3, 1, 2, 3, 3, 2, 4, 2, 2, 2, 4, 2, 3, 3, 2, 4, 3, 2, 4, 3, 3, 4, 2, 2, 3, 2, 2, 4, 3, 2, 5, 3, 2, 4, 5, 3, 4, 2, 4, 5, 4, 2, 4, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,14 COMMENTS This is related to the conjecture given in A223174 and A223175. For n > 8, a(12) = a(24) = 0 because A223174(12)= A223174(24)= 0. LINKS Michel Lagneau, Table of n, a(n) for n = 0..10000 EXAMPLE a(14) = 2 because 29 = 5+8*3 = 13+8*2 with 2 decompositions. a(23) = 3 because 47 = 7+8*5 = 23+8*3 = 31+8*2 with 3 decompositions. MATHEMATICA a[n_] := (ways = 0; Do[p = 2k + 1; q = (n-k)/4; If[PrimeQ[p] && PrimeQ[q], ways++], {k, 1, n}]; ways); Table[a[n], {n, 0, 90}] CROSSREFS Cf. A219254, A223174, A223175. Sequence in context: A330348 A117229 A264119 * A269972 A202205 A336123 Adjacent sequences: A225515 A225516 A225517 * A225519 A225520 A225521 KEYWORD nonn AUTHOR Michel Lagneau, May 09 2013 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 June 10 14:50 EDT 2023. Contains 363205 sequences. (Running on oeis4.)