A097442 - OEIS

%I #4 Oct 01 2013 17:58:02

%S 2,7,16,36,64,102,144,198,306,397,520,676,774,898,1116,1396,1575,1819,

%T 2097,2264,2557,2883,3267,3835,4296,4533,4830,5080,5394,6426,7275,

%U 7881,8285,9159,9784,10392,11213,11879,12651,13555,14080,15221,16016,16573

%N Integer part of the area of consecutive prime sided isosceles triangles.

%C The real part of these numbers is always irrational.

%F Consider prime isosceles triangles of sides (2, 3, 3), (3, 5, 5), ..., (x, y, y) where x is prime and y is the next prime after x. Then area = 1/2*x*sqrt(y^2-(x/2)^2). Output floor(area)

%o (PARI) f(n) = forprime(x=2,n,y=nextprime(x+1);a=1/2*x*sqrt(y^2-(x/2)^2);print1(floor (a)","))

%K nonn

%O 2,1

%A _Cino Hilliard_, Aug 22 2004