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 A128193 First differences of values of n for Cullen primes in A005849. 1
 140, 4572, 1082, 816, 11885, 13796, 177, 27187, 31169, 171594, 98856, 120624, 872929, 4973720, 351333 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Carlos Rivera's Problem 50 is devoted to this topic. If we pair differences according to magnitude, we first obtain 177-140=37 a prime. This raises the question as to whether there are other such prime values. LINKS Table of n, a(n) for n=1..15. Carlos Rivera, Problem 50. Is there a Cullen prime Cn with n prime?, The Prime Puzzles and Problems Connection. FORMULA a(n) = A005849(n+1) - A005849(n). - Michel Marcus, Sep 27 2020 EXAMPLE a(1)=140 because the first pair of n are 1 and 141. 141 - 1 = 140. CROSSREFS Cf. A005849, A128194. Sequence in context: A255775 A199831 A264310 * A061607 A223349 A282613 Adjacent sequences: A128190 A128191 A128192 * A128194 A128195 A128196 KEYWORD nonn,more AUTHOR Enoch Haga, Feb 18 2007 EXTENSIONS Offset 1 from Michel Marcus, Sep 27 2020 a(14)-a(15) added by Florian Baur, Sep 27 2020 STATUS approved

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Last modified February 27 16:21 EST 2024. Contains 370378 sequences. (Running on oeis4.)