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 A198628 #14 Dec 30 2024 17:56:07 %S A198628 1,3,15,81,435,2313,12195,63801,331395,1710153,8775075,44808921, %T A198628 227890755,1155180393,5839846755,29458152441,148335904515, %U A198628 745888593033,3746364947235,18799770158361,94271405748675,472449569948073,2366624981836515,11850654345690681,59323452211439235 %N A198628 Alternating sums of powers for 1,2,3,4 and 5. %C A198628 See A196848 for the e.g.f.s and o.g.f.s of such sequences for the numbers 1,2,...,2*n+1, and A196847 %C A198628 for the numbers 1,2,...,2*n. %H A198628 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (15,-85,225,-274,120). %F A198628 a(n) = sum(((-1)^(j+1))*j^n,j=1..5) = 1-2^n+3^n-4^n+5^n. %F A198628 E.g.f.: sum(((-1)^(j+1))*exp(j*x),j=1..5) = %F A198628 exp(x)*(1+exp(5*x))/(1+exp(x)). %F A198628 O.g.f.: sum(((-1)^(j+1))/(1-j*x),j=1..5) = %F A198628 (1-12*x+55*x^2-114*x^3+94*x^4)/product(1-j*x,j=1..5). %F A198628 A formula for the numbers of the numerator polynomial is given in A196848. %p A198628 A198628 := proc(n) %p A198628 3^n-4^n+1-2^n+5^n ; %p A198628 end proc: %p A198628 seq(A198628(n),n=0..20) ; # _R. J. Mathar_, May 11 2022 %t A198628 LinearRecurrence[{15,-85,225,-274,120},{1,3,15,81,435},30] (* _Harvey P. Dale_, Dec 30 2024 *) %Y A198628 Cf. A083323, A196847, A196848, A196837. %K A198628 nonn,easy %O A198628 0,2 %A A198628 _Wolfdieter Lang_, Oct 27 2011