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 A367247 #5 Nov 12 2023 13:31:31
%S A367247 0,7,131,1609,16415,150817,1296191,10641169,84520175,654958177,
%T A367247 4980233951,37312922929,276288797135,2026564724737,14750977566911,
%U A367247 106695818055889,767748717541295,5500729672814497,39270143125479071,279511731951144049,1984459091985376655,14059238393314971457
%N A367247 a(n) is the number of n-digit numbers whose difference between the largest and smallest digits is equal to 6.
%C A367247 a(n) is the number of n-digit numbers in A366963.
%H A367247 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (18,-107,210).
%F A367247 a(n) = 27*7^(n-1) - 47*6^(n-1) + 4*5^n.
%F A367247 a(n) = 21*a(n-1) - 146*a(n-2) + 336*a(n-3) for n > 3.
%F A367247 O.g.f.: x^2*(7 + 5*x)/((1 - 5*x)*(1 - 6*x)*(1 - 7*x)).
%F A367247 E.g.f.: (162*exp(7*x) - 329*exp(6*x) + 168*exp(5*x) - 1)/42.
%t A367247 LinearRecurrence[{18,-107,210},{0,7,131},22]
%Y A367247 Cf. A366963.
%Y A367247 Cf. A000351, A000400, A000420.
%Y A367247 Cf. A367243, A367244, A367245, A367246, A367248, A367249, A367250.
%K A367247 nonn,base,easy
%O A367247 1,2
%A A367247 _Stefano Spezia_, Nov 11 2023