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 A075322 Pair the odd primes so that the k-th pair is (p, p+2n) where p is the smallest prime not included earlier such that p and p+2n are primes and p+2n also does not occur earlier: (3, 5), (7, 11), (13, 19), (23, 31), (37, 47), (17, 29), ... This is the sequence of the second member of every pair. 3
 5, 11, 19, 31, 47, 29, 67, 59, 79, 103, 131, 97, 127, 167, 71, 181, 191, 173, 151, 233, 239, 223, 257, 277, 313, 251, 281, 163, 389, 353, 373, 347, 307, 337, 419, 431, 457, 443, 479, 397, 461, 523, 577, 509, 499, 541, 557, 563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Question: Is every prime p a member of some pair? a(n) = A075323(2*n). LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A075321(n)+2*n. a(n) = A075323(2*n). MAPLE # A075321p() implemented in A075321. A075322 := proc(n)     op(2, A075321p(n)) ; end proc: seq(A075322(n), n=1..60) ; # R. J. Mathar, Nov 26 2014 MATHEMATICA A075321p[n_] := A075321p[n] = Module[{prevlist, i, p, q }, If[n == 1, Return[{3, 5}], prevlist = Array[A075321p, n - 1] // Flatten]; For[i = 2, True, i++, p = Prime[i]; If[FreeQ[prevlist, p], q = p + 2*n; If[PrimeQ[q] && FreeQ[ prevlist, q], Return[{p, q}]]]]]; a[n_] := A075321p[n][[2]]; Array[a, 50] (* Jean-François Alcover, Feb 12 2018, after R. J. Mathar *) PROG (Haskell) a075322 = a075323 . (* 2)  -- Reinhard Zumkeller, Nov 29 2014 CROSSREFS Cf. A075321, A075323. Sequence in context: A106068 A304875 A164566 * A079850 A065995 A023245 Adjacent sequences:  A075319 A075320 A075321 * A075323 A075324 A075325 KEYWORD nonn AUTHOR Amarnath Murthy, Sep 14 2002 EXTENSIONS Corrected by R. J. Mathar, Nov 26 2014 STATUS approved

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Last modified June 24 01:40 EDT 2021. Contains 345404 sequences. (Running on oeis4.)