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 A139758 a(n) is the smallest prime such that (a(n) - the n-th prime) is a power of 2. 2
 3, 5, 7, 11, 13, 17, 19, 23, 31, 31, 47, 41, 43, 47, 79, 61, 61, 317, 71, 73, 89, 83, 211, 97, 101, 103, 107, 109, 113, 241, 131, 139, 139, 1163, 151, 167, 173, 167, 199, 181, 181, 197, 193, 197, 199, 263, 227, 227, 229, 233, 241, 241, 257, 283, 769, 271, 271 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It is only conjectured (see Cino Hilliard's comment at A094076) that this sequence is defined for all n. LINKS FORMULA a(n) = A000040(n) + 2^A094076(n). - R. J. Mathar, May 20 2008 MAPLE A094076 := proc(n) local k, p ; k := 0 ; p := ithprime(n) ; while not isprime(p+2^k) do k := k+1 ; od: k ; end: A139758 := proc(n) ithprime(n)+2^A094076(n) ; end: seq(A139758(n), n=1..80) ; # R. J. Mathar, May 20 2008 MATHEMATICA sp2[n_]:=Module[{p=Prime[n], k}, k=NextPrime[p]; While[!IntegerQ[Log[2, k-p]], k=NextPrime[k]]; k]; Array[sp2, 60] (* Harvey P. Dale, Dec 27 2019 *) CROSSREFS Cf. A094076, A033875. Sequence in context: A120637 A278454 A064534 * A306084 A060770 A246568 Adjacent sequences:  A139755 A139756 A139757 * A139759 A139760 A139761 KEYWORD nonn AUTHOR Leroy Quet, May 19 2008 EXTENSIONS More terms from R. J. Mathar, May 20 2008 STATUS approved

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Last modified September 18 22:56 EDT 2020. Contains 337174 sequences. (Running on oeis4.)