A090852 a(n) is the least positive integer such that the integer part of the arithmetic-geometric mean of a(n) and 1 is equal to n.

1, 4, 7, 10, 13, 16, 20, 24, 27, 31, 35, 39, 43, 47, 51, 55, 60, 64, 68, 73, 77, 81, 86, 90, 95, 100, 104, 109, 113, 118, 123, 127, 132, 137, 142, 146, 151, 156, 161, 166, 171, 176, 181, 186, 191, 196, 201, 206, 211, 216, 221, 226, 231, 236, 241, 246, 251, 256, 262

Offset: 1

Author

Paul D. Hanna, Dec 10 2003

Keywords

• nonn

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A090853, A090854.

Programs

Mathematica

Table[Ceiling[y /. FindRoot[Pi/(2*EllipticK[1 - y^2]) == n, {y, 2*n}]], {n, 1, 60}] (* Vaclav Kotesovec, Sep 28 2019 *)

Formula

floor( agm(a(n), 1) ) = n, for n>=1.