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 A260384 Maximal gap between successive elements of Pn with n >= 3. Pn : primes p <= A002110(n) such that q=2*A002110(n)-p is prime. (p, q) is a pair of centered primes at n-th primorial. 1
 6, 16, 44, 122, 268, 556, 886, 1446, 1964, 2900 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 LINKS EXAMPLE For n=3, primorial(3)=A002110(3) is 30 and P3 is (7, 13, 17, 19, 23, 29) because (53, 47, 43, 41, 37, 31) are all prime. The maximum gap between two consecutive terms of P3 is 6, obtained for (7,13) or (23,29), so a(3)=6. PROG (PARI) lstp(n)=my(v = []); pn = prod(i=1, n, prime(i)); forprime(p=1, pn-1, if (isprime(2*pn-p), v = concat(v, p))); my(w = vector(#v-1, k, v[k+1] - v[k])); vecmax(w); \\ Michel Marcus, Jul 24 2015 (PARI) a(n)=my(P=2*prod(i=1, n, prime(i)), r, last=P); forprime(p=2, P/2, if(isprime(P-p), r=max(r, p-last); last=p)); r \\ Charles R Greathouse IV, Jul 24 2015 CROSSREFS Cf. A002110. Sequence in context: A107614 A317758 A010915 * A126360 A264545 A296855 Adjacent sequences:  A260381 A260382 A260383 * A260385 A260386 A260387 KEYWORD nonn,more AUTHOR Jean-Marc Rebert, Jul 24 2015 EXTENSIONS a(10) from Charles R Greathouse IV, Jul 24 2015 a(11) from Charles R Greathouse IV, Jul 28 2015 a(12) from Charles R Greathouse IV, Jul 30 2015 STATUS approved

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Last modified May 17 15:35 EDT 2021. Contains 343980 sequences. (Running on oeis4.)