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 A367248 #5 Nov 12 2023 13:31:40
%S A367248 0,5,111,1601,19095,204545,2045511,19508081,179752215,1613908385,
%T A367248 14202967911,123028446161,1052237271735,8907026785025,74758478722311,
%U A367248 623053865857841,5162154289325655,42558224511290465,349394287423788711,2858263098464575121,23311522539676521975
%N A367248 a(n) is the number of n-digit numbers whose difference between the largest and smallest digits is equal to 7.
%C A367248 a(n) is the number of n-digit numbers in A366964.
%H A367248 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (21,-146,336).
%F A367248 a(n) = 23*8^(n-1) - 41*7^(n-1) + 3*6^n.
%F A367248 a(n) = 21*a(n-1) - 146*a(n-2) + 336*a(n-3) for n > 3.
%F A367248 O.g.f.: x^2*(5 + 6*x)/((1 - 6*x)*(1 - 7*x)*(1 - 8*x)).
%F A367248 E.g.f.: (161*exp(8*x) - 328*exp(7*x) + 168*exp(6*x) - 1)/56.
%t A367248 LinearRecurrence[{21,-146,336},{0,5,111},21]
%Y A367248 Cf. A366964.
%Y A367248 Cf. A000400, A000420, A001018.
%Y A367248 Cf. A367243, A367244, A367245, A367246, A367247, A367249, A367250.
%K A367248 nonn,base,easy
%O A367248 1,2
%A A367248 _Stefano Spezia_, Nov 11 2023