OFFSET
1,1
COMMENTS
LINKS
Jason Kimberley, Table of n, a(n) for n = 1..10000
FORMULA
Primes of the form (t1*t2-1)/2, where t1, t2 are twin primes.
EXAMPLE
t1 = 71,t2 = 73, (71*73-1)/2 = 5182/2 = 2591 = prime.
MATHEMATICA
Select[(Times[#, # + 2] - 1)/2 &@ Select[Prime@ Range@ 1000, PrimeQ[# + 2] &], PrimeQ] (* Michael De Vlieger, Nov 06 2015 *)
PROG
(PARI) for(n=1, 1e3, if(prime(n+1)-prime(n)==2 && isprime(k=(prime(n)*prime(n+1)-1)/2), print1(k", "))) \\ Altug Alkan, Nov 06 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Aug 20 2003
STATUS
approved