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 A061252 #27 Jan 20 2023 20:18:17
%S A061252 0,1,31,721,14911,289201,5386591,97576081,1732076671,30276117361,
%T A061252 522861237151,8942430185041,151728638820031,2557404559011121,
%U A061252 42864668012537311,715027614225987601,11878335717996660991
%N A061252 a(n) = 16^n - 15^n.
%C A061252 Number of ways to assign truth values to n quaternary conjunctions connected by disjunctions such that the proposition is true. For example, a(2) = 31, since for the proposition '(a & b & c & d) v (e & f & g & h)' there are 31 assignments that make the proposition true. - _Ori Milstein_, Dec 31 2022
%C A061252 Equivalently, the number of length-n words over the alphabet {0,1,..,15} with at least one letter = 15. - _Joerg Arndt_, Jan 01 2023
%H A061252 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (31,-240).
%F A061252 a(0)=0, a(n) = 15*a(n-1) + 16^(n-1). - _Vincenzo Librandi_, Feb 09 2011
%F A061252 a(0)=0, a(1)=1, a(n) = 31*a(n-1) - 240*a(n-2). - _Vincenzo Librandi_, Feb 09 2011
%F A061252 a(n) = A001025(n) - A001024(n). - _Michel Marcus_, Aug 26 2013
%t A061252 Table[16^n-15^n,{n,0,20}] (* or *) LinearRecurrence[{31,-240},{0,1},20] (* _Harvey P. Dale_, Jan 23 2021 *)
%o A061252 (PARI) a(n) = 16^n - 15^n; \\ _Michel Marcus_, Aug 26 2013
%Y A061252 Base 8: A016177, 4: A005061, 2: A000225, 10: A016189.
%K A061252 nonn,easy
%O A061252 0,3
%A A061252 _Frank Ellermann_, Jun 05 2001