OFFSET

1,1

COMMENTS

Such number digits after decimal point of number Pi where the approximation to the number Pi by a root of a polynomial of 2 degree does not improve the accuracy exactly n next digits.

EXAMPLE

a(1)=18 because 3.141592653589793238 (18 digits) is root of -3061495 + 674903*x + 95366*x^2 and 3.1415926535897932385 (19 digits) also is root of that same polynomial -3061495 + 674903*x + 95366*x^2.

CROSSREFS

KEYWORD

nonn,base,less,uned

AUTHOR

Artur Jasinski, Mar 15 2008

EXTENSIONS

There are comments in the entry for A138335 which may cast doubt on the validity of this and related sequences. - N. J. A. Sloane, Mar 19 2008

STATUS

approved