1,2

The sequence provides an indication of regions of nearly no

improvements of the sequence of convergents to Pi when measured by

the count of correct digits after rounding. A "plateau" of n consecutive integers

is defined by a(n) = j such that A138343(j) = A138343(j+n-1) and

such that none of the intermediate A138343 with index j+1 up to j+n-2 drop below this level.

a(3)=4 because the A138343(4) to A138343(6) are the earliest plateau of length 3.

The fact that there is a local maximum at A138343(5)=9 above the plateau is consistent with the definition.

Cf. A138335, A138336, A138337, A138338, A138343.

Adjacent sequences: A138336 A138337 A138338 this_sequence A138340 A138341 A138342

Sequence in context: A103227 A165415 A069199 this_sequence A107827 A070406 A063632

nonn,less,base,bref

Artur Jasinski (grafix(AT)csl.pl), Mar 16 2008

Definition and values adapted to redefined A138343 - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 01 2009