A090303 - OEIS

%I #9 Jul 29 2017 03:51:29

%S 0,0,0,2,3,0,5,3,7,5,0,7,11,0,13,11,7,13,17,3,19,17,13,19,23,0,17,23,

%T 19,13,29,0,31,29,7,31,0,0,37,23,31,37,41,3,43,41,37,43,47,0,41,47,43,

%U 37,53,0,47,53,31,43,59,0,61,59,37,61,0,0,67,53,61,67,71,0,73,71,67,73,2,3

%N Begin with n and consider numbers obtained by successively subtracting 2,3,5,7,11,...; a(n) = largest prime that arises, i.e., largest prime of the form n - sum prime(r), or 0 if no such prime exists.

%C a(p) = p-2 if p is larger member of a twin prime pair.

%C Conjecture: There are finitely many zeros in this sequence.

%F Largest prime of the form n - sum prime(r).

%o (PARI) a(n) = {p = 2; n -= p; while ((n > 0) && !isprime(n), p = nextprime(p+1); n -= p); max(0, n);} \\ _Michel Marcus_, Jul 29 2017

%Y Cf. A090304.

%K nonn

%O 1,4

%A _Amarnath Murthy_, Nov 30 2003

%E More terms from _David Wasserman_, Oct 27 2005