A024389 [ (4th elementary symmetric function of S(n))/(2nd elementary symmetric function of S(n)) ], where S(n) = {first n+3 positive integers congruent to 1 mod 4}.

2, 19, 72, 190, 409, 773, 1336, 2159, 3309, 4863, 6907, 9532, 12840, 16939, 21945, 27985, 35189, 43699, 53664, 65239, 78591, 93891, 111320, 131067, 153328, 178309, 206221, 237286, 271732, 309795, 351722, 397763, 448180, 503242, 563224, 628413

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Formula

Empirical g.f.: -x*(x^17 -2*x^16 +2*x^14 -x^13 -x^11 +2*x^10 -4*x^8 +4*x^7 +12*x^6 +21*x^5 +23*x^4 +27*x^3 +21*x^2 +13*x +2) / ((x -1)^5*(x^2 +x +1)*(x^4 +x^3 +x^2 +x +1)). - Colin Barker, Aug 16 2014

a(n) = floor(A024380(n) / A024378(n+2)). - Sean A. Irvine, Jul 06 2019