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 A187759 Number of ways to write n=x+y (0
 0, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 2, 0, 2, 1, 3, 2, 1, 2, 1, 2, 2, 2, 2, 3, 1, 3, 1, 2, 3, 2, 6, 1, 3, 1, 2, 4, 3, 4, 4, 1, 3, 1, 3, 5, 2, 6, 1, 3, 2, 2, 5, 2, 5, 2, 3, 1, 2, 3, 5, 2, 4, 0, 0, 3, 1, 6, 2, 3, 3, 1, 5, 1, 5, 3, 3, 3, 1, 4, 2, 3, 3, 0, 3, 3, 3, 4, 1, 3, 1, 2, 3, 2, 4, 2, 2, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,8 COMMENTS Conjecture: If n>200 is not among 211, 226, 541, 701, then a(n)>0. This essentially follows from the conjecture related to A219157, since n=x+y for some positive integers x and y with 6x-1,6x+1,6y-1,6y+1 all prime if and only if 6n=p+q for some twin prime pairs {p,p-2} and {q,q+2}. Similarly, the conjecture related to A218867 implies that any integer n>491 can be written as x+y (01600 not among 2729 and 4006 can be written as x+y (0

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Last modified April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)