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 A016161 #34 Nov 10 2024 09:24:50
%S A016161 1,12,109,888,6841,51012,372709,2687088,19200241,136354812,964249309,
%T A016161 6798573288,47834153641,336059778612,2358521965909,16540171339488,
%U A016161 115933787267041,812299450322412,5689910849522509
%N A016161 Expansion of g.f. 1/((1-5*x)*(1-7*x)).
%C A016161 Also, this is the number of incongruent integer-edged Heron triangles whose circumdiameter is the product of n distinct primes each of shape 4k + 1. Cf. A003462, A109021. - _R. K. Guy_, Jan 31 2007
%H A016161 G. C. Greubel, <a href="/A016161/b016161.txt">Table of n, a(n) for n = 0..1000</a>
%H A016161 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (12,-35).
%F A016161 From _R. J. Mathar_, Sep 18 2008: (Start)
%F A016161 a(n) = (7^(n+1) - 5^(n+1))/2 = A081200(n+1).
%F A016161 Binomial transform of A080962. (End)
%F A016161 a(n) = 7*a(n-1) + 5^n. - _Vincenzo Librandi_, Feb 09 2011
%F A016161 E.g.f.: exp(5*x)*(7*exp(2*x) - 5)/2. - _Stefano Spezia_, Oct 25 2023
%t A016161 CoefficientList[Series[1/((1-5x)(1-7x)),{x,0,30}],x] (* or *) LinearRecurrence[ {12,-35},{1,12},30] (* _Harvey P. Dale_, Nov 16 2021 *)
%o A016161 (PARI) Vec(1/((1-5*x)*(1-7*x))+O(x^99)) \\ _Charles R Greathouse IV_, Sep 24 2012
%o A016161 (Magma) [n le 2 select 12^(n-1) else 12*Self(n-1) -35*Self(n-2): n in [1..30]]; // _G. C. Greubel_, Nov 09 2024
%o A016161 (SageMath)
%o A016161 A016161=BinaryRecurrenceSequence(12,-35,1,12)
%o A016161 [A016161(n) for n in range(31)] # _G. C. Greubel_, Nov 09 2024
%Y A016161 Cf. A003462, A080962, A081200, A109021.
%Y A016161 Cf. A016162, A016163, A016164, A016165, A016166.
%K A016161 nonn,easy
%O A016161 0,2
%A A016161 _N. J. A. Sloane_