Search: id:A130098
Results 1-1 of 1 results found.

%I A130098
%S A130098 17,23,47,73,89,101,103,109,113,131,137,151,163,167,173,193,199,211,223,
%T A130098 233,241,257,269,271,277,281,311,313,317,331,337,359,367,379,383,389,
%U A130098 397,401,409,421,431,433,449,457,461,487,491,503,509,521,547,557,563
%N A130098 Primes prime(n) such that both of the numbers (prime(n+2)^2-prime(n)^2)/
               2 - 1 and (prime(n+2)^2-prime(n)^2)/2 + 1 are not primes.
%e A130098 a(1)=17 because (23^2 - 17^2)/2 - 1 = 119 and (23^2 - 17^2)/2 + 1 = 121 
               (119, 121 are not primes),
%e A130098 a(2)=23 because (31^2 - 23^2)/2 - 1 = 215 and (31^2 - 23^2)/2 + 1 = 217 
               (215, 217 are not primes),
%e A130098 a(3)=47 because (59^2 - 47^2)/2 - 1 = 635 and (59^2 - 47^2)/2 + 1 = 637 
               (635, 637 are not primes), ...
%p A130098 ts_p2_21:=proc(n) local a,b,i,ans; ans := [ ]: for i from 2 to n do a 
               := (ithprime(i+2)^(2)-ithprime(i)^(2))/2-1: b := (ithprime(i+2)^(2)-ithprime(i)^(2))/
               2+1: if not (isprime(a)=true or isprime(b)=true) then ans := [ op(ans), 
               ithprime(i) ]: fi od; RETURN(ans) end: ts_p2_21(500);
%Y A130098 Cf. A130761.
%Y A130098 Sequence in context: A086532 A159044 A126329 this_sequence A046123 A152292 
               A039319
%Y A130098 Adjacent sequences: A130095 A130096 A130097 this_sequence A130099 A130100 
               A130101
%K A130098 nonn
%O A130098 1,1
%A A130098 Jani Melik (jani_melik(AT)hotmail.com), Aug 01 2007

Search completed in 0.001 seconds