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 A063149 #24 Jun 05 2024 22:26:03
%S A063149 25,35,55,65,85,95,115,125,145,155,175,185,205,215,235,245,265,275,
%T A063149 295,305,325,335,355,365,385,395,415,425,445,455,475,485,505,515,535,
%U A063149 545,565,575,595,605,625,635,655,665,685,695,715,725,745,755,775,785,805
%N A063149 Composite numbers which in base 5 contain their largest proper factor as a substring.
%H A063149 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A063149 a(n) = 30*n-a(n-1) for n>1, a(1)=25. - _Vincenzo Librandi_, Aug 07 2010
%F A063149 From _Chai Wah Wu_, Jun 05 2024: (Start)
%F A063149 a(n) = a(n-1) + a(n-2) - a(n-3) for n > 3.
%F A063149 G.f.: x*(-5*x^2 + 10*x + 25)/((x - 1)^2*(x + 1)). (End)
%t A063149 Do[ If[ !PrimeQ[ n ] && StringPosition[ ToString[ FromDigits[ IntegerDigits[ n, 5 ] ] ], ToString[ FromDigits[ IntegerDigits[ Divisors[ n ] [ [ -2 ] ], 5 ] ] ] ] != {}, Print[ n ] ], {n, 2, 1000} ]
%o A063149 (PARI) a(n)=([0,1,0; 0,0,1; -1,1,1]^(n-1)*[25;35;55])[1,1] \\ _Charles R Greathouse IV_, Jun 05 2024
%Y A063149 Cf. A062238.
%K A063149 nonn,base,easy
%O A063149 1,1
%A A063149 _Robert G. Wilson v_, Aug 08 2001