This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A152106 #23 Jan 26 2025 15:13:11
%S A152106 1,9,85,837,8521,88929,944605,10155357,110061841,1199150649,
%T A152106 13109949925,143644498677,1576134831961,17309800577169,
%U A152106 190214028328045,2090997865462797,22991481397070881,252839829506640489,2780772863545070965,30585244671799959717,336414893599428810601
%N A152106 a(n) = (11^n + 7^n)/2.
%H A152106 Harvey P. Dale, <a href="/A152106/b152106.txt">Table of n, a(n) for n = 0..960</a>
%H A152106 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (18,-77).
%F A152106 a(n) = ((9 + sqrt(4))^n + (9 - sqrt(4))^n)/2.
%F A152106 From _Philippe Deléham_, Nov 26 2008: (Start)
%F A152106 a(n) = 18*a(n-1) - 77*a(n-2), n > 1; a(0)=1, a(1)=9.
%F A152106 G.f.: (1-9*x)/(1-18*x+77*x^2).
%F A152106 a(n) = (1/9^n)*Sum_{k=0..n} A098158(n,k)*9^(2*k)*4^(n-k). (End)
%F A152106 E.g.f.: exp(9*x)*cosh(2*x). - _Elmo R. Oliveira_, Aug 23 2024
%e A152106 a(3) = (11^3 + 7^3)/2 = 837.
%t A152106 LinearRecurrence[{18,-77},{1,9},30] (* _Harvey P. Dale_, Jan 26 2025 *)
%o A152106 (PARI) a(n)=(11^n+7^n)/2 \\ _Charles R Greathouse IV_, Aug 23 2024
%Y A152106 Cf. A098158.
%K A152106 nonn,easy
%O A152106 0,2
%A A152106 Al Hakanson (hawkuu(AT)gmail.com), Nov 24 2008
%E A152106 Extended beyond a(6) by _Klaus Brockhaus_, Nov 26 2008
%E A152106 More terms by _Elmo R. Oliveira_, Aug 23 2024