a(n) is the least number k that has exactly n divisors <= sqrt(k) of the form 4*j+1.

Terms

a(0) =1a(1) =25a(2) =90a(3) =585a(4) =1575a(5) =2475a(6) =5850a(7) =9945a(8) =16380a(9) =20475a(10) =36855a(11) =45045a(12) =69615a(13) =122850a(14) =135135a(15) =176715a(16) =218295a(17) =225225a(18) =495495a(19) =405405a(20) =348075a(21) =696150a(22) =675675a(23) =765765a(24) =1461915a(25) =1351350a(26) =2304225a(27) =1576575a(28) =4037670a(29) =2027025