A134780 The square root of A134779.

1, 2, 1, 2, 1, 3, -1, 6, -7, 19, -33, 73, -146, 311, -652, 1392, -2977, 6420, -13899, 30247, -66078, 144911, -318853, 703768, -1557718, 3456813, -7689531, 17142887, -38296408, 85715645, -192191445, 431647744, -970958480, 2187288804, -4934101775, 11144794835, -25203825094

Offset: 0

Author

Paul D. Hanna & Robert G. Wilson v, Nov 11 2007

Keywords

• sign

Crossrefs

Cf. A084202, A134779.

Programs

Mathematica

a[n_] := a[n] = Block[{k = a[n - 1] + 2, s = Sum[ a[i]*x^i, {i, 0, n - 1}]}, If[IntegerQ@ Last@ CoefficientList[ Series[ Sqrt[s + k*x^n], {x, 0, n}], x], k, k + 1]]; a[0] = 1; CoefficientList[ Series[ Sqrt[ Sum[ a[i]*x^i, {i, 0, 36}]], {x, 0, 36}], x]