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 A060483 #18 Mar 09 2024 12:42:40
%S A060483 3,57,717,7845,81333,825237,8300757,83202645,832809813,8331237717,
%T A060483 83324947797,833299785045,8333199127893,83332796486997,
%U A060483 833331185898837,8333324743497045,83333298973791573,833333195894773077,8333332783578305877,83333331134311650645
%N A060483 Number of 5-block tricoverings of an n-set.
%C A060483 A covering of a set is a tricovering if every element of the set is covered by exactly three blocks of the covering.
%H A060483 Andrew Howroyd, <a href="/A060483/b060483.txt">Table of n, a(n) for n = 3..500</a>
%H A060483 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (17,-84,148,-80).
%F A060483 a(n) = (1/5!)*(10^n - 15*4^n + 45*2^n - 40).
%F A060483 Generally, e.g.f. for k-block tricoverings of an n-set is exp(-x+x^2/2+(exp(y)-1)*x^3/3)*Sum_{k=0..inf}x^k/k!*exp(-1/2*x^2*exp(k*y))*exp(binomial(k, 3)*y).
%F A060483 G.f.: 3*x^3*(2*x+1) / ((x-1)*(2*x-1)*(4*x-1)*(10*x-1)). - _Colin Barker_, Jan 11 2013
%o A060483 (PARI) Vec(3*(1+2*x)/(x-1)/(2*x-1)/(4*x-1)/(10*x-1)+O(x^99)) \\ _Charles R Greathouse IV_, Jan 11 2013
%Y A060483 Column k=5 of A060487.
%Y A060483 Cf. A006095, A060484, A060485, A060486, A060090-A060095, A060069, A060070, A060051-A060053, A002718, A059443, A003462, A059945-A059951.
%K A060483 nonn,easy
%O A060483 3,1
%A A060483 _Vladeta Jovovic_, Mar 20 2001
%E A060483 More terms from _Colin Barker_, Jan 11 2013