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 A135456 #22 Mar 16 2024 17:25:38
%S A135456 5040,141120,2328480,29635200,322494480,3162075840,28805736960,
%T A135456 248619571200,2060056318320,16540688324160,129568848121440,
%U A135456 995210916336000,7524340159588560,56163512390086080,414847224363337920
%N A135456 Number of surjections from an n-element set onto a seven-element set.
%H A135456 G. C. Greubel, <a href="/A135456/b135456.txt">Table of n, a(n) for n = 7..1000</a>
%H A135456 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (28,-322,1960,-6769,13132,-13068,5040).
%F A135456 a(n) = 7^n -C(7,6)*6^n +C(7,5)*5^n -C(7,4)*4^n +C(7,3)*3^n -C(7,2)*2^n +C(7,1) with n>=7.
%F A135456 a(n) = A000771(n) * 7!. - _Max Alekseyev_, Nov 12 2009
%F A135456 G.f.: -5040*x^7/((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)*(6*x-1)*(7*x-1)). - _Colin Barker_, Oct 25 2012
%F A135456 E.g.f.: (exp(x) - 1)^7. - _Ilya Gutkovskiy_, Jun 19 2018
%t A135456 LinearRecurrence[{28, -322, 1960, -6769, 13132, -13068, 5040}, {5040, 141120, 2328480, 29635200, 322494480, 3162075840, 28805736960}, 25] (* _G. C. Greubel_, Oct 14 2016 *)
%Y A135456 Column k=7 of A019538 and A131689.
%Y A135456 Cf. A000918, A000919, A000920, A001117, A001118.
%K A135456 nonn,easy
%O A135456 7,1
%A A135456 _Mohamed Bouhamida_, Dec 15 2007
%E A135456 More terms from _Max Alekseyev_, Nov 12 2009