cp's OEIS Frontend

A117472 Values of c in a^2 + b^2 = c^2, where b - a = 17 and gcd(a,b,c)=1.

%I A117472 #7 Jun 13 2015 00:52:05
%S A117472 25,53,137,305,797,1777,4645,10357,27073,60365,157793,351833,919685,
%T A117472 2050633,5360317,11951965,31242217,69661157,182092985,406014977,
%U A117472 1061315693,2366428705,6185801173,13792557253,36053491345
%N A117472 Values of c in a^2 + b^2 = c^2, where b - a = 17 and gcd(a,b,c)=1.
%C A117472 b - a = 17 is the third term in A058529 The values of 'a' are defined by A117473
%H A117472 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,6,0,-1).
%F A117472 c(1)=25, c(2)=53, c(3)=137, c(4)=305, c(n) = 6*c(n-2) - c(n-4), if c > 4
%F A117472 G.f.: -x*(13*x^3+13*x^2-53*x-25) / ((x^2-2*x-1)*(x^2+2*x-1)). [_Colin Barker_, Dec 17 2012]
%e A117472 c(5) = 6*137 - 25 = 797
%e A117472 555*555 + 572*572 = 797*797, where 572-555 = 17 and gcd(555,572,797)=1
%Y A117472 Cf. A117473, A058529.
%K A117472 nonn,easy
%O A117472 1,1
%A A117472 Andras Erszegi (erszegi.andras(AT)chello.hu), Mar 19 2006