Voozh

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

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

FORMULA

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

MATHEMATICA

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

CROSSREFS

Cf. A090853, A090854.

Sequence in context: A310681 A143456 A310682 * A182112 A090955 A310683