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Numbers k such that gcd(2*k^7+1, 3*k^3+2) > 1.
0

%I #25 Jan 20 2024 09:24:29

%S 435,1598,2761,3924,5087,6250,7413,8576,9739,10902,12065,13228,14391,

%T 15554,16717,17880,19043,20206,21369,22532,23695,24858,26021,27184,

%U 28347,29510,30673,31836,32999,34162,35325,36488,37651,38814,39977,41140,42303,43466

%N Numbers k such that gcd(2*k^7+1, 3*k^3+2) > 1.

%C This GCD is 1163 if k == 435 (mod 1163), or 1 otherwise.

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).

%F a(n) = 435 + 1163*n.

%F a(n) = 2*a(n-1) - a(n-2).

%F G.f.: (435 + 728*x)/(1 - x)^2.

%e a(0) = 435, 2*435^7+1 = 5894606169966093751 and 3*435^3+2 = 246938627, gcd(5894606169966093751, 246938627) = 1163.

%t Table[435+n*1163,{n,0,37}] (* _James C. McMahon_, Jan 15 2024 *)

%K nonn,easy

%O 0,1

%A _Philippe Deléham_, Jan 15 2024