Numbers k such that sum_{i=1..k} d(i)^2 is a square c^2, where d(i) is the number of divisors of i.

Terms

a(0) =1a(1) =3a(2) =28a(3) =85a(4) =151a(5) =302a(6) =864a(7) =3197a(8) =4780a(9) =5438a(10) =5815a(11) =6413a(12) =7769a(13) =7985a(14) =11062a(15) =16672a(16) =24805a(17) =27379a(18) =35435a(19) =41718a(20) =45047a(21) =58383a(22) =69835a(23) =70235a(24) =76305a(25) =91178a(26) =95963a(27) =97763a(28) =103173a(29) =111375