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 A035048 #26 Jul 08 2025 21:29:55
%S A035048 1,1,4,3,23,11,176,25,563,137,6508,49,88069,363,91072,761,1593269,
%T A035048 7129,31037876,7381,31730711,83711,744355888,86021,3788707301,1145993,
%U A035048 11552032628,1171733,340028535787,1195757
%N A035048 Numerators of alternating sum transform (PSumSIGN) of Harmonic numbers H(n) = A001008/A002805.
%C A035048 p^2 divides a(2p-2) for prime p>3. a(2p-2)/p^2 = A061002(n) = A001008(p-1)/p^2 for prime p>2. - _Alexander Adamchuk_, Jul 07 2006
%H A035048 Robert Israel, <a href="/A035048/b035048.txt">Table of n, a(n) for n = 1..2000</a>
%H A035048 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%F A035048 G.f. for A035048(n)/A035047(n) : log(1-x)/(x^2-1). - _Benoit Cloitre_, Jun 15 2003
%F A035048 a(n) = Numerator[Sum[(-1)^(k+1)*Sum[(-1)^(i+1)*1/i,{i,1,k}],{k,1,n}]]. - _Alexander Adamchuk_, Jul 07 2006
%F A035048 a(n) = numerator((-1)^(n+1)*1/2*(log(2)+(-1)^(n+1)*(gamma+1/2*(psi(1+n/2)-psi(3/2+n/2))+psi(2+n)))), with gamma the Euler-Mascheroni constant. - - _Gerry Martens_, Apr 28 2011
%p A035048 S:= series(log(1-x)/(x^2-1), x, 101):
%p A035048 seq(numer(coeff(S,x,j)), j=1..100); # _Robert Israel_, Jun 02 2015
%t A035048 Numerator[Table[Sum[(-1)^(k+1)*Sum[(-1)^(i+1)*1/i,{i,1,k}],{k,1,n}],{n,1,50}]] (* _Alexander Adamchuk_, Jul 07 2006 *)
%o A035048 (PARI) a(n)=numerator(polcoeff(log(1-x)/(x^2-1)+O(x^(n+1)),n))
%Y A035048 Cf. A035047, A002428, A001008, A058313, A061002.
%K A035048 nonn,easy,frac
%O A035048 1,3
%A A035048 _N. J. A. Sloane_