OFFSET
1,1
COMMENTS
Minimal integer m such that m=p(n)+q=sum of 2 primes, where p(n)<=q is the n-th prime and there is no prime r<p(n) such that m-r is prime. - Robin Garcia, Feb 12 2005
The increasing subsequence k(n), such that for all m>n, k(m)>k(n) is A025018, and the associated sequence of primes is A025019. - David James Sycamore, Feb 05 2018
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 1..977 (from the web page of Tomás Oliveira e Silva)
Tomás Oliveira e Silva, Goldbach conjecture verification
EXAMPLE
a(4)=30=7+23 because p(4)=7, q=23 is prime and there is no prime r<p(4)=7 such that a(4)-r is prime.
PROG
(MATLAB) p1 = primes(1000000); d(1, :) = p1; d(2, :) = d(1, :) - d(1, :); i = 4; k = 1; n = 0; while i <= 5000000 while not(isprime(i - d(1, k))) k = k + 1; end; if d(2, k) == 0 d(2, k) = i; if k == n + 1 while d(2, n+1) > 0 n = n + 1; end; if n > 0 d(2, 1:n) end; end; end; k = 1; i = i + 2; end; - Lei Zhou, Jan 26 2005
(PARI) Gold(n)=forprime(p=2, n, if(isprime(n-p), return(p)))
a(n, p=prime(n))=my(k=2); while(Gold(k+=2)!=p, ); k \\ Charles R Greathouse IV, Sep 28 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane, May 05 2007; b-file added Nov 27 2007
STATUS
approved