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A090855
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 2^n.
3
1, 4, 10, 24, 55, 127, 288, 640, 1408, 3069, 6642, 14281, 30544, 65028, 137896, 291399, 613885, 1289715, 2702909, 5652038, 11795170, 24570079, 51095155, 106092067, 219972452, 455493427, 942031726, 1946056082, 4015916211
OFFSET
0,2
FORMULA
floor( agm(a(n), 1) ) = 2^n, for n>=0.
MATHEMATICA
Flatten[{1, Table[Ceiling[y /. FindRoot[Log[Pi/(2*EllipticK[1 - y^2])] == n*Log[2], {y, n*2^n}, MaxIterations -> 1000]], {n, 1, 50}]}] (* Vaclav Kotesovec, Sep 28 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 10 2003
STATUS
approved