%I M3338 #32 Dec 19 2021 00:18:15
%S 1,4,8,21,39,92,170,331,593,1176,2118,3699,6658,11347,19760,32746,
%T 54854,90245,149906,237953,387937,608531,970912,1510331,2380015,
%U 3610620,5634251,8474110,12934092,19440955,29291690,43233800,64825830,94779612,139820232
%N Number of nonzero elements in the character table of the symmetric group S_n.
%C John McKay (email to _N. J. A. Sloane_, Apr 23 2013) observes that A061256 and A006908 coincide for a surprising number of terms, and asks for an explanation. - _N. J. A. Sloane_, May 19 2013
%D J. McKay, personal communication to N. J. A. Sloane, circa 1991.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%t a[n_] := Count[FiniteGroupData[{"SymmetricGroup", n}, "CharacterTable"], k_ /; k != 0, 2]; Array[a, 10] (* _Jean-François Alcover_, Oct 21 2016 *)
%o (GAP) A006908 := n -> Sum(Irr(CharacterTable("Symmetric", n)), chi -> Number(chi, x->x<>0)); # _Eric M. Schmidt_, Jul 13 2012, revised Sep 05 2012
%Y Cf. A006907, A061256.
%K nonn,nice
%O 1,2
%A _Simon Plouffe_ and _N. J. A. Sloane_
%E More terms from _Eric M. Schmidt_, Jul 13 2012