cp's OEIS Frontend

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

%I A180743 #10 Mar 30 2012 18:35:54
%S A180743 1,2,3,4,9,10,27,57,69,70,267,429,1059,1227,1479,2547,2787,3249,3459,
%T A180743 3537,4089,4719,5097,6267,6357,6567,6957,8997,9039,10089,12039,12819,
%U A180743 13719,16689,16977,17289,17919,18909,19377,19419,19749
%N A180743 Ascending sequence of numbers such that the sum of any two distinct elements (even + odd) is a prime number.
%e A180743 70 + 69 = 139 is prime ;
%e A180743 70 + 57 = 127 is prime ;
%e A180743 70 + 9 = 79 is prime ;
%e A180743 70 + 3 = 73 is prime ;
%e A180743 70 + 1 = 71 is prime.
%p A180743 with(numtheory):nn:=50: T:=array(1..nn): T[1]:=1:T[2]:=2:a:=2:a0:=1:a1:=1:for
%p A180743   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 A180743   p from 1 to a do: if n=T[p] then i:=0:else fi: x:=n+T[p]:if type(x, prime)=true
%p A180743   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:
%K A180743 nonn
%O A180743 1,2
%A A180743 _Michel Lagneau_, Jan 22 2011