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%I #16 Feb 11 2024 17:09:58
%S 1,34,259,1092,3333,8294,17927,34952,62985,106666,171787,265420,
%T 396045,573678,809999,1118480,1514513,2015538,2641171,3413332,4356373,
%U 5497206,6865431,8493464,10416665,12673466,15305499,18357724,21878557,25919998
%N One sixtieth the product of primitive Pythagorean triangles' sides whose odd values differ by 2.
%C If Y and Z are 2-blocks of a (2n+1)-set X then a(n-2) is the number of 7-subsets of X intersecting both Y and Z. - _Milan Janjic_, Oct 28 2007
%H Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Two Enumerative Functions</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-15,6,-1).
%F a(n) = n*(16*n^4 - 1)/15.
%F G.f.: x*(x^4+28*x^3+70*x^2+28*x+1) / (x-1)^6. - _Colin Barker_, Oct 06 2014
%t LinearRecurrence[{6,-15,20,-15,6,-1},{1,34,259,1092,3333,8294},30] (* _Harvey P. Dale_, Feb 11 2024 *)
%o (PARI) Vec(x*(x^4+28*x^3+70*x^2+28*x+1)/(x-1)^6 + O(x^100)) \\ _Colin Barker_, Oct 06 2014
%Y Cf. A081752.
%K easy,nonn
%O 1,2
%A _Lekraj Beedassy_, Apr 18 2003
%E More terms from _Ray Chandler_, Oct 28 2003