a(n) = 2nd elementary symmetric function of the first n+1 positive integers congruent to 1 mod 4.

Terms

a(0) =5a(1) =59a(2) =254a(3) =730a(4) =1675a(5) =3325a(6) =5964a(7) =9924a(8) =15585a(9) =23375a(10) =33770a(11) =47294a(12) =64519a(13) =86065a(14) =112600a(15) =144840a(16) =183549a(17) =229539a(18) =283670a(19) =346850a(20) =420035a(21) =504229a(22) =600484a(23) =709900a(24) =833625a(25) =972855a(26) =1128834a(27) =1302854a(28) =1496255a(29) =1710425