A180743 Ascending sequence of numbers such that the sum of any two distinct elements (even + odd) is a prime number.

1, 2, 3, 4, 9, 10, 27, 57, 69, 70, 267, 429, 1059, 1227, 1479, 2547, 2787, 3249, 3459, 3537, 4089, 4719, 5097, 6267, 6357, 6567, 6957, 8997, 9039, 10089, 12039, 12819, 13719, 16689, 16977, 17289, 17919, 18909, 19377, 19419, 19749

Offset

1,2

Links

Table of n, a(n) for n=1..41.

Example

70 + 69 = 139 is prime ;
70 + 57 = 127 is prime ;
70 + 9 = 79 is prime ;
70 + 3 = 73 is prime ;
70 + 1 = 71 is prime.

Maple

with(numtheory):nn:=50: T:=array(1..nn): T[1]:=1:T[2]:=2:a:=2:a0:=1:a1:=1:for
  k from 3 to nn do:id:=0:for n from k to 20000 while(id=0) do:n1:=irem(n, 2):i:=0:for
  p from 1 to a do: if n=T[p] then i:=0:else fi: x:=n+T[p]:if type(x, prime)=true
  then i:=i+1:else fi:od: if (i=a1 and n1=0) or (i=a0 and n1=1) then T[k]:=n:a0:=a0+irem(n1+1, 2):a1:=a1+n1:printf(`%d,  `, n):a:=a+1:id:=1: else fi:od:od:

Crossrefs

Sequence in context: A366913 A329573 A291163 * A162662 A376656 A068334

Adjacent sequences: A180740 A180741 A180742 * A180744 A180745 A180746

Keyword

nonn

Author

Michel Lagneau, Jan 22 2011

Status

approved