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 A356890 a(n) is the first twin prime that begins a sequence of exactly n twin primes under the map t -> 3*t+2. 0
 7, 3, 19, 40951819, 12454922269 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..5. EXAMPLE a(3) = 19 because 19 is a twin prime, 3*19+2 = 59 is a twin prime, and 3*59+2 = 179 is a twin prime, but 3*179+2 = 539 is not a twin prime. MAPLE f:= proc(p) local q; option remember; if isprime(p) and isprime(p + 4*(p mod 3) - 6) then 1 + procname(3*p+2) else 0 fi end proc: f(3):= 2: A:= Vector(4): count:= 0: for p from 5 by 2 while count < 4 do v:= f(p); if v > 0 and A[v] = 0 then A[v]:= p; fi od: convert(A, list); CROSSREFS Sequence in context: A357200 A284477 A145399 * A160797 A050013 A161417 Adjacent sequences: A356887 A356888 A356889 * A356891 A356892 A356893 KEYWORD nonn,more AUTHOR J. M. Bergot and Robert Israel, Sep 02 2022 EXTENSIONS a(5) from Jean-Marc Rebert, Sep 08 2022 STATUS approved

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Last modified September 16 18:48 EDT 2024. Contains 375977 sequences. (Running on oeis4.)