A111159 Numbers k such that A111075(k) is odd.
1, 3, 4, 6, 12, 16, 24, 25, 27, 48, 49, 54, 64, 75, 96, 100, 108, 121, 147, 150, 169, 192, 196, 216, 243, 256, 289, 294, 300, 361, 363, 384, 400, 432, 484, 486, 507, 529, 588, 600, 625, 675, 676, 726, 768, 784, 841, 864, 867, 961, 972, 1014, 1024
Offset: 1
Keywords
Formula
Conjecture: A111075(n) is odd whenever: (i) n = m^2 for all m>=1 such that 3 does not divide m, or (ii) n = 3*A028982(m) for all m>=1. Also, A028982 gives "Union of nonzero squares and twice squares."
It is not difficult to show that the conjecture is true. - Max Alekseyev, Oct 12 2005