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A108783
Positions of 1's in A083952, where A083952 gives the integer coefficients a(n) of A(x), where a(n) = 1 or 2 for all n, such that A(x)^(1/2) has only integer coefficients.
4
0, 2, 6, 10, 12, 26, 30, 32, 36, 50, 52, 56, 60, 62, 126, 130, 132, 136, 150, 152, 160, 164, 166, 170, 172, 174, 176, 180, 184, 192, 194, 198, 200, 202, 214, 216, 220, 226, 228, 230, 234, 236, 240, 242, 244, 260, 262, 264, 272, 274, 278, 282, 286
OFFSET
1,2
LINKS
MATHEMATICA
a[n_] := a[n] = Block[{s = Sum[a[i]*x^i, {i, 0, n - 1}]}, If[ IntegerQ@ Last@ CoefficientList[ Series[ Sqrt[s + x^n], {x, 0, n}], x], 1, 2]]; Union@ Table[ If[ a[n] == 1, n, 0], {n, 0, 300}] (* Robert G. Wilson v, Nov 25 2006 *)
CROSSREFS
Cf. A083952, A108337, A108338. See A111363 for another version.
Sequence in context: A214963 A140776 A277238 * A235989 A066679 A086123
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, following a suggestion from Paul D. Hanna, Jun 30 2005
STATUS
approved