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.

6, 16, 44, 122, 268, 556, 886, 1446, 1964, 2900

Offset: 3

Author

Jean-Marc Rebert, Jul 24 2015

Keywords

• nonn
• more

Examples

			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.
		

Crossrefs

Cf. A002110.

Programs

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

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