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 A242656 #3 May 30 2014 18:05:38 %S A242656 1,20,90,259,602,1230,2298,4015,6655,10569,16198,24087,34900,49436, %T A242656 68646,93651,125761,166495,217602,281083,359214,454570,570050,708903, %U A242656 874755,1071637,1304014,1576815,1895464,2265912,2694670,3188843,3756165,4405035,5144554,5984563,6935682 %N A242656 Mahonian numbers T(n,6) (cf. A008302). %C A242656 45 years ago this was A000711, but it was dropped during the preparation of the 1973 Handbook of Integer Sequences. %p A242656 g := proc(n, k) option remember; if k=0 then return(1) else if (n=1 and k=1) then return(0) else if (k<0 or k>binomial(n, 2)) then return(0) else g(n-1, k)+g(n, k-1)-g(n-1, k-n) end if end if end if end proc; %p A242656 [seq(g(n,6),n=4..40)]; %Y A242656 Cf. A008302. %K A242656 nonn %O A242656 4,2 %A A242656 _N. J. A. Sloane_, May 30 2014